LOTR: by what sorts of processes did Sauron reconstitute himself and his power after losing the Ring?

[Jack_Burden]

@Roderick_Femm

So how did he do it, and why did it take so long? Those are my main questions. How does a Maia who has lost so much of himself reconstitute his strength? Does any being help him to do this (as distinct from helping him wreak his evil will on the world)? In his voluminous tomes, does Tolkien answer this crucial question?

Just wondering if the OP was at all prompted by S2 Epi1 of The Rings of Power? Because there is a scene where Sauron reconstitutes himself from incorporeal form there and it was not at all what one would expect. Not like anything in anything I’ve ever read from Tolkien, but then nothing else in that show is either.