You have to work out what his 3bet-fold, 3bet-call, and 3bet-jam range look like. And you need to have an idea of what he calls your 4bet with. Rake structure matters too.
Also, you are supposed to be 3betting a ton BU vs CO, hr may not even 3bet enough. Look at GTO Wizard 9 handed 150bb deep, 10% 2bb rake cap, 3x open CO vs BU, 3x 3b:
And this is your response 4betting 28.5bb
His is his response to 4bet:
And your response to 5bet jam:
When figuring out what to 4bet, you should think about blockers, equity retention, and playability postflop.
Blockers are fairly simple. You want to unblock hands that will fold and block hands that continue. A is going to be the most important blocker to have followed closely by K. In a nutshell, this is because you block AA, KK, and AK. You also want your kicker to unblock folds. A5s and A4s unblock lots of folds that contain a J through 6.
Equity retention is about folding out hands that have you dominated while keeping in hands you are live against and even sometimes hands you are ahead of. For example, A5s should fold out AJo, ATo, most AQo, and A6s-A8s which dominate us. But it can keep in hands like KQs which we are ahead of. In other words, when we get called, we aren't just isolating villain to a range so strong it destroys us.
Playability postflop means you have hands that flop well. If they flop a pair it tends to be pretty strong, like AQo. They also tend to be suited and connected so they flop draws or can turn equity, so other than high pairs, AQo, and AKo+ (some worse hands in really late configuration like BvB, BU vs SB, BU vs BB), most of 4bets are going to be suited and have some connectivity.
You should take a look at the GTO ranges, compare those to villain, and adjust accordingly. Is villain going to 3bet KQo, AQo, and AJo and then call a 4bet with those hands? Then you probably want to 4bet more linearly like TT+, AQo+, AJs+, KQs. Hands like A5s, A4s, KTs, go down a lot in value when villain doesn't fold to 4bet properly since their equity retention is not as strong. Hands that dominate them aren't folding enough.
On the other hand, if villain is 3betting very wide and over-folding to 4bet, we should go nuts with our 4bets.
If villain 3bets much tighter than GTO, we should overfold to 3bets and not 4bet very much.
So you have to mentally construct villain's 3bet fold and 3bet continue range. Remember there are way more offsuit combos than suited combos. If he 3bet folds AQo, KQo, QJo, then think KJs, AJs, A5s, A4s. If he is 3bet folding pure with ATo, KTo, QJo, JTo, maybe we 4bet more A9s, K9s, JTs. Unblock his offsuit folds and/or 4bet suited hands that are dominated by his offsuit hands that he folds, but playable vs his continue range.