Currently 70% of the flights are made by 15% of the population (1). If you start adding increasing taxes on each additional flight you take, it would rapidly curtail a lot of the travel I'd expect.
I am sure a lot of us in Europe (and perhaps USA? Not sure if it is as prevalent) in the past have been guilty of taking a "weekend break" somewhere that is a 1 or 2 hr flight away where the tickets usually cost something like £30-40 return on Easyjet or Ryanair (and often cheaper than a taxi to get to the airport!)
E.g. after 2 flights a year, start adding £50 per flight (so 3rd is +£50, 4th +£100, 5th +£150 etc etc). Suddenly your £30 return flight from London to Lisbon/Rome/Dublin/Barcelona/Berlin etc is no longer so absurdly cheap. Put all the proceeds from the tax into decarbonisation and fast intercity rail.
That would soon make people (myself included) think twice about taking "frivolous" city-breaks every month or so where you fly out after work on a Friday and come home again Sunday night ready to be back at your desk on Monday morning.
1 - https://fullfact.org/economy/do-15-people-take-70-flights/