So right now I have a 21.5" 4k (LG) display above my 2021 16" MBP, and today's the first time I noticed how the interface is sized based on the higher ppi of the MacBook Pro display (UI elements are noticeably smaller), which does make me question whether they'd make things smaller on a 32" 7k display.
(Normally I just have email, text documents or web browser windows on the laptop display, so I hadn't noticed how more specific UI elements shrank inside other apps.)
And I'm sure I've said this before, but for me, on a 27" 4k display @ "Default for Display" (I think this is what you referred to as 2x scaling? maybe not), the interface is huge. I have it scaled to 2560 x 1440 and the interface size matches the 4k 21.5" display next to it; but you get some blurring. Ok a lot of the time, but sub-par overall.