How many frames should each match be?

Matches are set as a race to: race to 2 means the first player to win two frames wins the match.

When you set the tournament up, you pick one race for every round and one for the final. A longer final makes it feel like a final.

For a knockout, you can go further in the tournament's settings and set each round on its own, like shorter early rounds and longer ones as it gets serious.