I just want to say, the visual style on display here is incredible - excellent use of post processing effects and materials, really hard to believe this is an Unreal Engine game. The scenery and level design was also very good and definitely reminiscent of the era of gaming you were going for.
While I understand that this is mostly a reimplementation of the base gameplay of Superliminal, I think you've done a pretty good job of that - it certainly doesn't seem like an easy mechanic to replicate, and I thought the actual scaling worked fairly well in practice.
On the flip side, the engine may have caused a bit of friction regarding the physics aspect of the game - I had quite a few of the scalable objects bounce around randomly after scaling them, and had to fight to keep a few of them on their buttons. Also ended up soft-locking myself the first time around with the mirror, as it fell over once after I went through it.
Think there's definitely some interesting ideas you could explore with this concept, and would love to see some of the additional ideas you've previously mentioned implemented on top of the base mechanic. Great job on the entry!