If you 4 bet your KK in a ring game and then someone else goes all in.... Without any info on the player it seems obvious that AA, KK, or QQ are in their hand. AA being the most likely for most online ring game players.
If the person going over top was somewhat short stacked, AA becomes less likely. If you've been paying attention and picked up on a pattern of over aggressive preflop play, then AA becomes less likely as well.
If you're multi-tabling without a HUD, then you're on your own. It's tough to spot betting patterns while playing 4+ tables, so in that case youre on your own.
If you make the same move in a tournament, your opponent's range widens to AA,KK,QQ,JJ,AK,AQ. (Provided they have at least an average stack). If they have 20BBs or less, their range is basically any pocket pair or AK,AQ,AJ,A10,KQ. I NEVER fold KK preflop in a tourney and I'm yet to run in to aces. Players in tournaments are just so much weaker.