Yes, you can finish Normal and then go into Elite, finish that and then go into Ultimate. That’s the “traditional” way to play because new characters always start at L1 on Normal; higher difficulties can only be unlocked by a character that’s finished the previous difficulty and only that character can go into them.
Crate did add the Merit Tokens a while back so people could skip to a higher difficulty if they wanted to avoid the 3 playthroughs every time.
And with the latest version of the game you can now do this:
