I have slightly x-shaped legs (and flat feet), is there anything i can do to correct my legs?

X legs: Orthotics - custom inserts for the shoes would help the torquing effect on your hips and knees. A good arch support stops the hips and knees from internally rotating and flattening your feet out. There are some corrective surgical procedures available, but would need to have your hips, knees, and feet checked out.

Not sure I : Completely understand what an x shaped leg is but sounds like you may have genu valgum where the knees turn in and "knock". As a podiatrist, my first thought would be to get you into orthotics. If after orthotics you complained of pain perhaps some form of correction of the feet. You did not mention pain though, hence, orthotics and conservative tx.