There is no additional risk. The risk comes into play once you go for owo in the first place, owo is a higher risk than using a condom for a bj. However the risk of contracting anything is quite low and almost anything you could get would be very treatable and temporary in any case. It's an acceptable risk for most.
But once you opt for owo, french kissing the lady won't increase your risk of contracting anything in almost any fashion. Basically, get tested at the minimum once a quarter like you should anyway and carry on as normal.