I’m inclined to say no, at least if we want to be careful.
Cultural relativism is the following claim:
CR: An action is morally permissible just in case it is accepted by your culture.
Thus, according to cultural relativism, the very same act can be both morally permissible and morally impermissible since the act may be accepted by one culture and not accepted by another culture. So, according to cultural relativism a single act can enjoy disparate moral statuses. The important point though is that the act has those properties in virtue of CR – in particular, in virtue of the objective moral truth that is CR. So, on this picture there are objective moral truths (or at least one, but you could get more by looking at the entailments of CR).
Consider now evidentialism. Evidentialism is the following claim:
E: S is justified in believing p just in case S’s evidence supports p.
Is evidentialism a kind of epistemic relativism? It doesn’t seem to be, yet it shares some features with CR. Different people can have different bodies of evidence, and thus different beliefs will be justified for them. Things could be such that S is justified in believing p and S’ is not. But the justificatory status that p has for these individuals, it has in virtue of E – in particular in virtue of the objective epistemic truth that is E.
So, the verdicts that E gives about beliefs and that CR gives about actions, are all given in reference to objective truths. I think that is reason to not consider either E or CR kind of relativism. If E and CR *are* to count as relativisms, it becomes *really* hard to see what would make a view not a relativistic view.