Polymarket offers creator markets, which enables trusted punters with ability to launch their own markets. Quickest way is to hit one of those up, and they will make you a price (and often times even match your bet .. in which case you should be cautious if they are very eager to take it :) ).

Second option is request for polymarket, they will usually not take long-term bets.

Third options, is to use UMA backbone (Optimistic Oracle v3), and spin up your own contract based on their code, as it is publically available. This is most flexible, but you may struggle to find liquidity because you are on your own.