Heist style game

Hi. I am minor indie developer. Made some small game projects, now dream minor heist/payday/gta style project, which contain enemies like polices, few cars, maybe helicopter and minor small heists. it is or sounds big project, but have many experience for that kind of project? I dream that someday someone maybe make some heist asset to marketplace where to start. i have some vehicles, npc etc, but making proper ai and transition from vehicle to other is difficult

I would even buy that kind of template 200-300$ where is enemy and enemy car chasing and transition between player and few different style vehicles