You mean increase the "Accuracy"? Then yes obviously. Though first, their accuracy is increased by 1% for every level higher you are too them starting at 30% Source.
Some good ways to increase Acc for OHKO moves are:
Though be warned most of the time OHKO moves are banned from competitive play.
the accuracy of all OHKO moves is decided by :
users level - targets level + 30
so higher your level more the accuracy