Clamshell or ranch casing seems like you have a mid century ranch not really suited for wainscoting. Posting photos of the rooms might garner you more suggestions.

Yep, that base indicates a more modern home and is not suitable for wainscoting.

Instead of a wainscoting that directly connects the baseboards to a chair rail you could do box molding centered between the two with a more eased or bullnosed edge that relates but doesn’t match exactly the baseboard along with a chair rail with a simpler profile.

Is removing the quarter round and baseboard an option to have wainscoting go to the floor?

@David Major I googled and found this:

https://agirlsguidetohomediy.com/2021/07/02/board-and-batten-without-removing-baseboards/

https://www.ramblingrenovators.ca/2016/09/what-you-need-to-know-before-you-diy-shiplap.html

None with that clamshell base. Because anything applied to the wall above the clamshell is going to stand proud of baseboard and look awful.

If you are going to the expense and effort of B&B or wainscoting, why would you cut corners & try to save the baseboard? And have the finished product look subpar if not downright awful & silly? You need to decide what style you want and then match the appropriate base, style, size & scale, to the rest of the wall.

IMO we need more info and pics . Post both here in comments do not start another post . IMO what you show is not good with wainscoting so I need more info.

Thanks all for the input! Yes it is indeed ranch-ish style, mid 1960s but a split level. We need a cohesive vision, and I think we can/should push it craftsman.

I’m not opposed to new baseboard, but was wondering if anything could complement what’s there. The more I find out, looks like the last guy painted over most of the trim with no sanding, so they probably all should be ripped out anyways.

We’re thinking of re doing this whole entry area to give nice flow into the house. The idea of the day is “French countryside mud room”

Please don’t try to turn a split level into a craftsman, it rarely works. Just try to make it into the best version of itself (mid century split level) it can be and personalize it with art and accessories. Based on these photos invest in quality consistent hardwood flooring throughout.