https://www.pcgamer.com/gta-onlines-halloween-event-features-murder-mayhem-and-free-t-shirts/

Six Adversary Modes will offer double RP and GTA  during the event, including:   e fun-filled festival of costumes and junk food that we're used to. Tricks definitely lead the way in the GTA Online's Halloween event, and by "tricks" I mean even more  murder than usual. 

Six Adversary Modes will offer double RP and GTA money during the event, including: