Say you were a beginner in poker and the showdown comes and you lay down your hand as KK proposing to go with pair of kings. The cards on the table are TJQA4. The suits are such that you could have a royal flush.
Assuming an opponent has a hand that is better than a pair of kings but worse than a royal flush, do you win because your hand can form a royal flush, or do you lose because you didn't notice the royal flush and tried to go with pair of kings?
In other words, do you choose how to play your hand in the end, or is the most valuable combination of cards automatically and involuntarily chosen?