The select-fire hop-up is currently not available in Season 10 of Apex Legends, but players have found a glitch that allows certain weapons to behave as if it were attached. If performed correctly, the Prowler will be able to fire in a fully automatic fashion and the Havoc can be fired as a semi-automatic. A TikTok from Aug. 13 shows how the glitch is done in the Battle Royale.
To perform the glitch, players will need to find either a Prowler or a Havoc and a Triple Take from the care package. First, drop the Prowler or Havoc on the ground so that the weapon can be traded for the Triple Take. Then toggle off the precision choke for the Triple Take. After the precision choke has been turned off, begin trading the Triple Take for either the Prowler or Havoc on the floor but toggle the Triple Take's precision choke back on as the weapon are switching. If timed properly, then the weapon the Triple Take is traded for will be picked up already in the gun's alternate fire pattern. The timing can be tricky, so remember to be patient as you're attempting this glitch.
If attachments are picked up from the ground for either the glitched Havoc or Prowler then the glitch will be undone. There is a workaround however. If the attachments are in the player's inventory before the glitch is done then they can be attached and not undo the select fire glitch.