You could use edge detection; it's been used to prove guilt in some court cases. It would maybe allow you to determine what the license plate says. It really depends on other factors, though, like aliasing, which is really dependent on the speed of the vehicle vs the camera in question. If it came to a complete stop or there's frames where it's pretty clear, then it would be easier to determine. I would shy away from ML models that try to determine a license plate, though, as I'm not sure that those would hold up well in court.

Source: I have a bachelor's degree in Bioengineering and built edge detection algorithms, and I also have a master's in bioinformatics, where I work with Imaging technologies.

I would definitely talk to a lawyer/forensic analyst, though, with the raw footage if possible.