I am running my 2021 3.0 in "AS" or A Street at SCCA Autocross events. The best 200 TW tries for this only come in 18" wheel sizes. The rules will let you go up or down one inch in diameter but the width has to be the same. Finding a 18X9 wheel with the correct bolt pattern was difficult. I bought a set of the 21 Supra 2.0 18 inch wheels from my local dealer. They are the same width, bolt pattern and offset.
What tire size and brand did you go with in 18"? I'm currently running the OE 19" wheels with RE71 tires in (265/35 - 285/35) combo. I have to say the car handles pretty good with this setup and I've been pleased with the feedback and handling. If I were to buy another set I would probably go with a 30 series tire and bump up to (275/30 - 295/30) combo. But the selection in this combo is very dismal.