The matching console table in your first set of photos looks too tall for the back of your sofa. Be sure to note measurements. Agree the dropleaf, while pretty on its own, doesn't seem a good fit for a console table in your space. Not sure why... maybe because looking at it straight on means not fully appreciating the ironwork behind the leaf. I usually love a fabric or leather ottoman for practicality (additional seating) but your furniture arrangement doesn't need any additional seating. I think a solid coffee table would work best.

I don't think the rug is too large since you have the fireplace blocked off and you could pull it still further under the couch, but I would choose one that also has some warm colors in it so that you're not so much in the cool blue/gray spectrum. I would move the large chair to sit straight against the window wall. When you've chosen your rug, buy some pillows that have the colors of the rug in them. I would declutter the mantel and put a large and colorful painting there, or a mirror that could reflect a large painting placed over the couch. I would also urge you to buy some curtain panels for the windows, in a cream color and thick material to soften this room. The room seems to be dominated by children's things, and perhaps some of that could be removed, although some of it is also inevitable when they're a certain age. A coffee table would certainly be a great addition, as would an end table and lamp next to the large chair. The coffee table and end table should not be the same. One of them could be glass and meta, preferably the end table, where it's less likely that little bodies and heads would hit against it.

I think that rug makes the room look smaller. Either no rug or a rug that fills the room would be my choice. I think, also, remove that table from the window area and put a little round side table (if you need one) out of sight between the chair and the window wall (okay--one for each chair, if you need it). I have these little 12" diameter tables that are perfect for putting a drink on and take up little space. I think some nice, colorful drapes/curtain panels and coordinating accent pillows on the chairs would be great. The goal would not be to COVER the windows, but to draw attention to them (they are great windows!). It sounds like your goal is to be able to seat a bunch of folks for gatherings in the that room or not? What is the main goal of the room?

I love this one because it has some darker colors that repeat your lampshades, pillows, etc. I think it really grounds the sitting area. https://incrediblerugsanddecor.com/products/karastan-spice-market-alcantara-saphire-area-rug This is lovely: https://www.potterybarn.com/products/channing-tufted-wool-persian-style-rug-red/?pkey=call-rugs&isx=0.0.2322 This looks gorgeous in there. Grays and beiges: https://incrediblerugsanddecor.com/products/karastan-euphoria-rhodes-ash-grey-area-rug . I don’t know if you like animal prints, but I think a zebra rug would look sharp in there, too. Faux or cowhide.