You can delay your turn until the end of the combat round (lower icon on the right edge of the screen).
Well, that's more of a "skip this round" option but yes, I've seen that.
One of the advantages of having a high initiative ought to that you can choose *when* to act, though. As in "after this specific person, who has buffs to cast" rather than "not at all this round."
I don't think I've ever seen that in a game system, though, so never mind, I guess.
