Try Ikea Billy, which won't match your armoire but I don't know if that matters to you. I currently have a Target striped fabric toy chest in my tv room. It matches nothing in the room but it does keep the toy cars and squishy sand hidden, lol.

What about some kind of trunk behind the sofa?

trunk is a good idea. or something like a hinged bench? this way everything is hidden. maybe on casters so it can roll in and out?

or, maybe a bench w/baskets

So, you want hidden storage for toys?

A trunk can be good storage, however, it is likely a "trunk" would be too low and thick/deep for that space for any practical purpose for putting something there such as for holding decorations and/or flower planters -- unless, perhaps, you are just wanting a spacer to keep the sofa away from the windows. Trunks not usually good toy boxes since they can smash little fingers closing on them.

You might consider a "sofa table" or a tv table or a entry/foyer/hall table with a bottom shelf for baskets for toys that can be accessed from the sides -- so no need to pull everything out of place to get to it.

How long is your sofa?

Are you at all DIY inclined?

If you can find or create a unit with access to the two ends to two shelves for baskets for toys,

https://www.younghouselove.com/at-long-last-a-completed-console/

and you could have a top lid for accessing the center for easier to reach stuff like large stuffed toys.

https://www.pinterest.com/pin/430304939380848794/

And could add a lamp and /or flower pot or game board other decorative item atop the two ends.

This could work:

https://www.jossandmain.com/--Parker-Etagere-Bookcase-GRKS3886-L38-K~J000728622.html?refid=GX432413120327-J000728622_474685176&device=c&ptid=899403058042&targetid=pla-899403058042&network=g&ireid=70805952&PiID%5B%5D=474685176&gclid=EAIaIQobChMI4q2y7-GE6QIVhZ-fCh2Low4SEAQYAyABEgLw1vD_BwE

Or this:

https://www.jossandmain.com/furniture/pdp/blairs-etagere-bookcase-ivbx2679.html

https://www.worldmarket.com/product/wood-and-metal-3-tier-willard-storage-shelf.do?sortby=ourPicks&from=fn

https://www.worldmarket.com/product/wood-and-metal-3-tier-willard-storage-shelf.do?sortby=ourPicks&from=fn

IMO a box in a closet for when the grand kids come over I think a book case there no matter what the style will not look good. If you want you could do trunk for the kid stuff you could. I found with our grandkids they liked only certain books and they brought favoriite toys with them for the visit.

If you want a box with a lid, then, in lieu of a "trunk", you might consider a storage ottoman or upholstered bench ( as suggested by Beth H. ) but, again, make sure the lid cannot slam down on little fingers -- and know that it will not fit well behind your sofa and become a chore trying to get to it there.

suez, that's why I posted a narrow one w/casters. it's easy to roll in and out.

OP could also do a little cube ottoman with storage and stick that in the corner, unless there is room for them elsewhere.

something like this could also double as a space for the kids to play games, or eat. But not drink wine!

It doesn't appear that there is a lot of room for turning a long table or bench, etc. to remove it from behind the sofa on the corner side so getting to all of it might be a challenge. Any storage piece put behind the sofa might be better suited if it didn't need to be removed to access what's in it.

I do like the little cube ottomans, Beth H. is suggesting. Finding a corner where they'd fit if you didn't want to use them as a footrest would be a lot easier than finding a place for a larger piece -- any kind of larger storage piece -- that you might want/need to be able to move about to access what's in it.

With a reversible top, the cube ottoman could even be plant stands. You wouldn't even need the table that fits between four of them with the + shaped legs -- a sanded painted piece of plywood or a Carrom board [https://en.wikipedia.org/wiki/Carrom] could turn several ottoman into a larger table for monopoly, jig saw puzzles, board games, hobbies -- versatility -- to keep children occupied.

Do let us know what you choose.

About the glass panels: You could wrap them in tissue paper and store them behind the cabinet just to their left -- once wrapped, you could even tape them to the back of the cabinet if you were worried they'd not stay put or be seen underneath the cabinet.

Thank you all so much for these great suggestions. What do you all think of this?

https://www.jossandmain.com/furniture/pdp/crestover-etagere-bookcase-j000016946.html?piid=1402948698

White or silver?

I'd prefer to hide kid toys but that's me. If you're thinking about that small three shelf bookcase, you obviously don't have a lot of kid stuff to store. Would everything fit in that armoire somewhere?

Do the grandkids have sleepovers at your house? Do you have a guest bedroom? Mine have their books in nightstands with shelves in "their" bedroom here. Even though they are all of 8 years old and tell me they're "big" now, they still love to dive into that toy chest and dig out their "baby" (as they call them) things to play with.

I think a cube ottoman in a patterned fabric that coordinates with the rest of your room would look better than a small bookcase in that space. If you have space elsewhere in the room for another one, I'd get a pair - they can always be used as regular accents after the grandkids outgrow them.

We have toys on every floor., lol This would hold some of their books, a game or two. Maybe a basket holding other items. I was going to put a plant on top since it is near a window with good light. So maybe go with safe white color or jazz it up with the silver? I could always paint later

hey all I finally made a decision! I have bins behind the sofa for toy storage. You cannot see them unless you kneel on couch and look over. And I have ordered this from Serena and Lily to store more items. https://www.serenaandlily.com/south-seas-side-cart/m12094.html It will go in the corner.

Finally arrived and just what I needed. I plan to hang artwork above and perhaps a small plant on top of cart. Rest of cart will store paper pencils books and small toys for kiddos

I think this little corner turned out very pretty and functional!