A cottage that needs the ornate metal columns replaced.

My thought was mid-century craftsman because those rails were very common then ... but more more common on ranch style brick subdivision homes than on craftsman homes that tended to have larger square wood posts, often atop pillars made of the same block or brick as the foundation -- at least that's what I remember from my own home town.

The metal porch posts and railings appear to be in good shape and doing their job well; and if maintained (properly prepped and painted as needed) they'll likely last a very long time. So, no, you don't need to replace the metal railings unless you are one of those people who prefer to follow fads and choose style over function ... and IF are willing to pay for it -- replace any wood you use for style as it fails (a lot quicker than properly maintained metal rails would).

I actually prefer the porch posts and rails white; however, I do notice you have a black ?metal? lamp post so if black metal is your preference, or if you prefer the same color as your siding or any other color for your porch rails and posts, then there is no reason why your porch posts and railings should not reflect your personal color taste.

You have a really nice looking home, including the porch, so I hope you are able to take the time to enjoy it, especially in spring and fall.

Yiu may be abke to box in the metal supoorfs but it looks like a craftsman that was modified. Do you have a historical society or a local book that may have pictures of your home feom the 1920’s/1930’s?

Black metal railing and hand rails for steps are not at all uncommon even now, even for wood decks and porches. https://www.decksbyschmillen.com/metal-railings-a-custom-deck-build-popular-choice/

It is more the vertical posts - not the rails -- that may seem to date the porch; and, if that (dated style) matters to you and you want a change, then at least consider painting all the railing and posts black to begin with. Then you could have the option to clad the metal vertical posts atop the pillars (with posts made for that or with treated lumber or plywood) and paint that wood the same color as the siding of your house -- but leave the (black) railings visible, thus keeping the strength of the metal in place and the option to "go back to" metal posts, should you, or a subsequent buyer of your home, decide to do so at a later date.

Or leave the rails and wood white.

This is the Zillow list photo fyi. I've added some personal touches but haven't done any work to the exterior. Interesting to note the mishmashes of style that have happened over time. Since we'd like to plan renovations, I just want to make sure I have a basic understanding of the home to make some style choices. Trying to sort of peel back the layers to figure out the original qualities and what was added on. Tozmo1 is right, there is an addition to the side, and I think the idea of the wood being replaced by the railing makes a lot of sense too.

I've gone back and forth on the black vs white paint question too

Part of its charm is that it looks a bit added-on-to over time.

The colours are attractive but to my eye the brick is too bright for the more muted tones of the roof and siding. The bright red draws the eye where it should go to the front door. I'd tone down the colour of the brick with a wash or stain. Romabio is the product you want. You could whitewash it, or apply a paint/wash with a more brown vs red brick colour.

If you are curious enough to spend a few dollars on checking out the visual, you could measure the width of the metal columns and invest in at least a couple of treated boards the same width and cut to the height of the metal part of the columns and, painted the color you want for your posts and railing, attach them to the two center columns -- you should be able see the difference in the look from the road without cladding the full post or just add boards to both front and back of the posts without creating a larger box. On the upside ... if you like flower hanging baskets, with wood on the posts, you could add a pair of brackets for hanging baskets of flowers or solar lights, or bird feeders or wind chimes or ... etc.

My mom's decorating books from the 1950s talked about modernizing houses from early in the 20th c. by removing heavy porch posts and railings and replacing them with lighter looking ornamental iron or steel, and removing those old fashioned stained or leaded glass windows with picture windows. This is a 1920ish bungalow added onto and "modernized" in the middle of the 20th c.

(Why people can't see that they are doing the same sorts of inappropriate things to 40-70 year old houses now, that's another story)

Probably looked like this originally. Might not have even had a railing on the stairs as many of the old bungalows didn't. Adding the ornamental railing was probably considered an upgrade and a show of wealth. Same reason my 90 year old mom requires wall to wall carpet over her hardwood floors. Only poor people didn't have wall to wall in her childhood days.