Can the Relax pass be applied to a relay module?

for example tvm.relax.transform.RewriteCUDAGraph

No, Relax passes cannot be directly applied to relay module. But you can generate a relax module from relay using the tvm.relay.testing.relay_translator.from_relay(...) function, and then you can apply any relax pass.

If you have relay passes that you work with, you could apply your relay passes, then traslate to relax module and then apply the relax passes and then generate code from relax.