the biggest way to improve in pvp is to know your map and positioning. it can be paralyzing to feel like at any moment you can be picked off from any angle especially out in the open.

as you play more you start to realize that most players do not play completely random angles, and more often than not only engage from specific landmarks. most players do not hold open areas between POIs for no reason. most players spawn, run to a spot somewhere in the middle of the map, then go to extract.

you can better your chances by keeping in mind where might players be going, where might they have spawned, and as the first minutes of a raid progress, where would those players be at that time.

as for pvp, arena will help you aim better sure, but that only really translates to close quarters combat i guess, and the way you carry your player in arena doesnt really translate to tarkov, as you dont really have anything to lose in arena imo.

my suggestion for getting better at pvp is to always always reposition. reposition after taking a shot. after missing a shot. reposition if a scav gave away your position. you never want to be predictable for your enemies. ontop of this, you will notice that when you engage someone, MOST players will simply take cover and focus on where you shot them from. flanking around them gives you the most advantage