@JohnFromGWN I think he means basically like, your player character completely becomes an NPC that is fully controlled by the game and he wants to just watch that character from a 3rd person camera.

I am thinking Menyoo but the problem is when you add an NPC to Menyoo's Object Database the ped just being stationary like it's AI functions are disabled.
If I remember correct, after you removing the ped from database the ped regains it's AI and just keeps walking, using random sceneario points too.

@12d3 I am not entirely sure will this work and I don't have the game to try at this moment but, you can maaayybe try this. First you need Menyoo. Then after you open the game, use Menyoo's Object Spooner with F9.

Right click to any NPC you want and select "Entity is in Database". This will make the NPC stop.
Then right click on your character and select Entity is in Database.
Then disable "Dynamic" and "Collision" options for yourself.
After that go to Attachment Options. Select "Attach to Something" and attach your character to the ped you to want to watch. (The one you added to Entity Database)

If your character's position doesn't properly attaches right on the NPC, you can move yourself towards the NPC with X, Y, Z options. Pitch, Roll, Yaw if needed as well.
Once your character is properly positioned, disable "Visible" option and this will make you invisible. You can also enable Invincible so you don't die.
Now is the problematic part.
To make the NPC regain it's AI, you need to remove it from Menyoo's Entity Database. To do that, right click on that NPC and uncheck "Entity is in Database".
Now the problem is once you do that this might detach your character from the NPC but you miiigght be stayed attached as well, I'm not sure. If you stay attached, then you can just watch that ped doing whatever he/she does Runs, shoots, walks, uses scenario animations and so on...

Though I don't think it will just get in to a car and drive then stop somewhere and get out. The NPCs getting on cars and driving away and the NPCs parking their cars and getting out are scripted events I believe and I don't know how to trigger that script for a character