In the "I Walk the Line" mission, you can fight the boss Sasquatch. After defeating her, manually save and immediately reload. She will appear on the floor "alive," allowing you to kill her again for repeated XP, Street Cred, and cash rewards.
Mastering the Grind: Infinite Money and XP Guide for Version 1.39 Infinite money and xp 1.39
For modern titles like or Roblox that frequently update, "infinite" XP is often found through AFK (Away From Keyboard) methods: In the "I Walk the Line" mission, you