RISC these days really refers mostly to uniformity with a bit of simplicity bolted on the side. Big instructions sets aren't really avoidable in practice, but the advantage AArch64 and RV64 have over X86 in theory is that they aren't totally insane (e.g. AArch64 is fixed width) and reliant on lots of trickery to preserve a machine model from the 70s.

RISC-V basically eliminates a lot of microarchitectural state (flags), whereas AArch64 updates that state conditionally. We will find out which approach is superior soon.