Keep in mind it's client side and not synced so each player will see different peds.
mp.game.ped.removeScenarioBlockingAreas();
mp.game.ped.setCreateRandomCops(true);
mp.game.ped.setCreateRandomCopsNotOnScenarios(true);
mp.game.ped.setCreateRandomCopsOnScenarios(true);
mp.game.vehicle.setRandomTrains(true);
mp.game.vehicle.setRandomBoats(true);
mp.game.vehicle.setGarbageTrucks(true);
mp.game.streaming.setPedPopulationBudget(3);
mp.game.streaming.setVehiclePopulationBudget(3);
mp.game.streaming.setReducePedModelBudget(false);
mp.game.streaming.setReduceVehicleModelBudget(false);
mp.game.vehicle.setAllGeneratorsActive();
mp.game.vehicle.setAllLowPriorityGeneratorsActive(true);
mp.game.vehicle.setNumberOfParkedVehicles(-1);
mp.game.vehicle.setDistantCarsEnabled(true);
mp.game.vehicle.displayDistantVehicles(true);
mp.game.graphics.disableVehicleDistantlights(false);
mp.game.ped.instantlyFillPopulation();