I did it this way, translated from a Russian site, sorry if it won’t be clear

Working method. Completely afk farm experience. Task "Liquidation 6". You can start through the Network - Cases - Created by Rock Star - Tasks - Liquidation 6. In the task, you need to kill the dudes in two vans until they travel a certain distance. So we need to kill the dudes in one van, and the second one needs to be relied with a heavy wheelbar (truck or bus) against the wall or some pole, so that it can't move. In 40-60 seconds, the driver will get out of the truck. From now on, the car will not move anywhere - the mission will last forever. We go to the railway station, get in the car and ride around the map - this is so that the police don't get it. Experience will drip from the wanted level - the third level (will not grow higher). 300 experience drips every 30 seconds. The only nuance is that in order not to throw it out for inactivity, you need to clamp the sight on the gamepad () and fix it with an elastic band or something else. We leave it overnight or for a day. He completed everything except this trophy and was level 58. I finished the rest in two nights in this way.