One thing that i figured out after years of traveling (and i tried a lot): try to stay up till 10pm even if you are collapsing(go out and walk till 10pm). Stay in the bed no matter what, even if you woke up 2am stay till alarm at 7am. Exercise (not kidding here) do light jumps, burpees, or run or walk. Drink a lot of water.
Lots of water. I’ve found that most of my jet lag symptoms from international flight were correlated to symptoms of estrogen imbalance (and im a guy). I started taking DIM when I travel and things got MUCH better. Also, magnesium before bed to regulate sleep schedule + zinc to prevent getting sick while traveling. Added bonus is that those two together increase testosterone levels, which makes you just feel better.
Try adjusting to destination time while still in the flight. If it's noon at the destination stay awake, if it's night try and sleep. The airlines don't help with this and turn the lights off at the wrong times so it's a struggle but it gives you an extra day head start on getting over the jet lag.