Always 4Bet with AK? Or call 3Bet? I speak broadly against a single opponent.
And the other question, always 4Bet with AA? So in general lines too.
This is not so easy, cause your position at the table, your stack size, and the upcoming players attitude will determine how to play these amazing pre-cards.
Without knowing these circumstances, I would say, 4-bet is just too big. Around 2.5-3 bet is pretty solid to maybe catch some players into the action, cause with these cards theres no need to scare others away. Unless you are smaller stack, you can push to all-in in the spirit of maybe one person will call you.
Don't be afraid of these combinations to play with them. Most of the times you 'll profit them, but sometimes need to get rid of if the party will turn and will be against us.
Use your time wisely to think, and think with others minds as well, and everything is gonna be okay.