Just go with whatever size you would get a regular supreme tee shirt in, thats the size I wear in their picket tees which are similar to those halftone ones
Went to SF store yesterday, S logo denim jacket was clean af, tried on a L from my normal M and it fit perfect, but at almost $400 after tax im good, track jacket material was nice, felt thicker than prior seasons. Bags are nice, gonna cop navy duffle or backpack soon.