Requesting a detailed breakdown on xbox one x resolution

I’m playing on xbox one x and trying to see if 1440p will work. So my question is to any Devs who’ve worked on the Xbox one x enhancement of the Handsome Collection. Which resolutions are the Handsome Collection capable of running at natively, and how are the achieved in the Xbox one x video settings?

4k looks great but the stability of the 60fps mark isn’t amazing during action intense sequences, so I’m trying to run it at 1440p to get a more stable 60. Will it actually render at native 1440p, or is it just going to downscale 4k/upscale 1080p? The xbox’s (allow 4k) video setting seems to keep it rendering at 4k and downscales to 1440 because it basically looks the same as native 4k. Running at 1440p without the (allow 4k) setting looks a bit better than 1080p, but I can’t tell if the difference is merely upscaling of a 1080p source.

This isn’t at all meant as a criticism of the framerate drops that happen on the xbox one x. I understand that there are such things as hardware limitations. I just want to know how it works and can’t find anything online that spells it out. I figured the best course of action is to try and get a detailed explanation from someone who actually worked on, or knows the mechanics of it.