The rotors are cross-compatible. When new, Shimano rotors are 1.80mm thick, and SRAM centerline rotors are 1.85-1.90mm thick. I’m currently running SRAM Centerline X rotors with Di2 setup on my 2020 Domane and it works great (I just think the CLX rotors look better 
).
As far as changing rotor size, yeah, I guess check with the frame manufacturer, although if they state max=160mm dia, you can use that, I reckon.