NL200 KQo

Preflop,
If his SB steal is 45% you should 3bet it for value, but if you think he is tighter vs you then just calling is fine. Though a merge 3bet can still be good against a perhaps 35% open.

Flop,
Your hand is strong enough to be raised for value. But it is a little bit thin, you don't want to stack off with it, and it plays well on most turns with a call. So just calling is fine as well.

Turn,
Call, very standard.

River,
Value betting is a bit thin with a flush and 3 different straights available. If you can make a read that his BBX range is weak, meaning you think he triple barrels a flush/straight/set most of the time, so you are good most of the time when he checks, you can make a thin value bet. Your bet is fine, but certainly a bit thin. If I saw you betting that there I would adjust by checking more flushes to you, and check raise those + some bluffs.

His play with QQ is fine on all streets. His hand is barely strong enough to value bet river, so he could do that, but it wouldn't gain much over checking. Since he blocks your top pairs and doesnt block your bluffs (45 at least) it's fine to play it as check call.

You say XC is bad in his spot because you don't value bet much worse. I don't agree with that logic. XC is a two part line. first he needs to think about check versus bet, and like I said, betting it himself is not that great, though certainly fine. the second part, calling your bet, well since you are value betting a few worse hands it is a snap call of course.

how is turn a standard call?
id say its at best breaking even or very marginally profitable.

vs 45% open, 90% cbet fcy on the flop, vilain vbetting KQ+ this is what i get for the turn:

Var 1: semibluffing frequency of vilain with {Js} or higher (flushdraws).
Var 2: raw str8draw (no Xs).

reasonable assumptions would be:
- 70% bluffs with flushdraws
=> breakeven point is at 50% for his str8draw.
These numbers are with hero realizing 100% of his equity on the river, which is not happening?
Given vilain's turn sizing, the board texture, hero's perceived range which could include most spades and QT, these are actually optimistic.

Js6d > KQo in this spot.