@kastro152 OpenIV is able to change nearly anything model/texture related like cars,streets,signs,clothes and so on and intensitys like lights and effects.
Scripts either create something completely new like dealing with drugs or vehicle persistence or add existing things to singleplayer like robbing banks quick note tho it's not 1:1 as it's just not possible or takes to long but its pretty close.
This link is pretty useful: link
Cheers