If you can do a 20 rep set easy just keep working on your bench, if not “grease the groove” as it were and work towards doing a 20 rep set. This is just to build a base doing like a 100 pushups won’t do anything for maximal strength. From there work on your bench including variations like decline bench and close-grip, heck try dips, if you can do more than 10 add weight with a belt.