Car thief 6 MOD Thread

Hello everyone, I am interested in modding some elements of this game called Car thief 6. However, the game is stored almost entirely in the (.exe) file. I've managed to open it with the software called Resource Tuner; but I didn't find any way to make the type of changes to the game as I'd hoped. If anyone with more Modding experience could help me out I would appreciate it.

Interestingly, the game allows you to add your own vehicles and people; but you can't add more items or weapons. This is one of the main things I had hoped to change.