how can i find someone by the license plates number?

In the UK, accessing personal details from a license plate is restricted due to privacy laws. Only police, DVLA,

You can’t legally find someone’s details from a license plate in the UK due to privacy laws. Only police, DVLA, or insurers can access this info for legal reasons. Avoid online “lookup” services—they’re often scams.

For DVLA-approved number plates, check Easy Number Plates.