On a K-high, two-tone board that completes a flush, A6o should bet for value on the river, and a medium-to-large sizing is preferred.
Flop K42cc, SPR ~3.1. This texture is semi-wet and favors our opening range slightly. Solver leans toward checking our whole range here, with some medium c-bets mixed in; A6o with A-high and a backdoor flush draw fits well into the check bucket. Checking keeps our range protected and avoids overplaying a marginal high-card hand on a board where BB can have plenty of Kx and decent draws.
Turn Jd brings us a strong flush draw and improves our range advantage. Solver likes a mix of checking and betting here, with a small 1/3-pot sizing performing well. The small 3BB bet into 9.5BB works well as a semi-bluff: we apply pressure to BB’s Kx and weaker pairs while still having a strong draw to realize on many rivers.
River 3d completes the flush and we now hold the nut flush with SPR ~1.7. Solver prefers a medium-to-large sizing here (≈66–125% pot) to extract from worse flushes and strong Kx/Jx. Our 13.2BB bet into 15.5BB (≈85% pot) is very close to the preferred medium size and is a solid value bet.