In Arc Raiders, players can communicate in voice chat not only with allies, but also with opponents. A PC Gamer journalist talked about how this feature can be used to increase the chances of survival.
A plea for mercy can sometimes work, but if the enemy has already knocked the player down, it is unlikely that he will take pity.
Ellie Gould suggested a specific solution that just works - you need to start complaining about your life:
Sometimes politeness can work, but if you've already been knocked down, they're unlikely to care much about good manners. So you have a few options. The first is to fall into real despondency. I'm talking about a tragedy on the level of a shrimp from "Shark Tale". I've been lucky a couple of times when I started telling a heartbreaking story about how hard the year had been and how little joy was left in my life - usually people either left me, allowing me to crawl away, or even picked me up with a defibrillator. For this I always shared loot with them.
There is another option: you can bribe the enemy. If there is a valuable improvement in the inventory (or the user is not shy about lying), then it can be hidden in a hidden pocket - in this case, the enemy will not be able to take it from the corpse and he may agree to spare the player.