Pretty much every Disney film not completed on film (so anything up to The Rescuers Down Under) has only ever been rendered to 2K (so everything from Beauty And The Beast onwards). Yes, this includes all the CGI stuff, including all the Pixars.
There *has* been a recent switch to native 4K (I believe Coco and Frozen II were among the first), but for a long while it was felt that the added resolution wasn’t a significant benefit worth the added rendering time.
Knowing that some collectors won’t purchase upscaled titles, and wanting to be able to market the "true 4K" nature of a source on D+ (ironic, given that streaming bandwidth can’t really quite handle the resolution and metadata without a higher element of compression), there has been a move to master in native 4K recently, presumably akso while rendering times are reduced as well.
Of course, all digital live action films of the 90s and 00s were all 2K as well (essentially HD), and even films shot after that In formats such as 3.5, 4 and 6.5K have usually been finished to a 2K digital interpositive. It’s only really been in the last five years that films have largely moved to 3.5 and 6.5K production and been mastered in native 4K, and those would mostly be the very big budget movies. I believe The Last Jedi was Disney's first completely native 4K release, shot and finished at the higher resolution.
But it’s still largely the norm to finish at 2K (!) and then upscale for a 4K presentation, adding HDR to boot color and luma depth as the main "selling point", but even here — after an initial getting "excited" with the tools — there has been a recent scaling back in the amount of HDR applied to images, and a regular comment you hear in post houses or, indeed, reviews of titles is to give it a "light HDR pass" (which is also kind of an oxymoron that belies an understanding of what HDR is and how it works).
