If you wish to use a 160mm rotor on the rear side, you will need to use a third-party adapter.
TRP adapters can be used as-is without any modification.
In the case of SHIMANO adapters, the mounting bolts are of a special design, and the pin section may interfere with the caliper. In such cases, you will need to modify the bolt by cutting the interfering part.
Please follow the adapter’s installation instructions to ensure proper mounting.