I've already pretty extensively played Portal, Portal 2 and Neon White and im looking for something new.

any racing game i personally recommend rally trophy and supert mario kart

STAR WARS EPISODE I: RACER

The most Portal Like Games to me are things like The Talos Principle... distantly followed by Antichamber.

Kind of weird that the Talos Principle community does Single Segment when it's Testing Chambers are basically numbered and seperated like Portals are...

Hill Climb Racing 2

Real ones playing Go! Go! Beckham! Adventure on Soccer Island, tbh. Good IGT system with any and hundo.

The Super Monkey Ball series has fun IL runs.