What a number plate can and cannot tell you
Every vehicle registered in India has a record in Vahan, the national registration database run by the Ministry of Road Transport and Highways. A registration number is enough to read that record.
What comes back is the vehicle: make, model and class, registering RTO and state, registration date, fuel type, insurance company and policy validity, PUC validity, fitness expiry for commercial vehicles, hypothecation status, and permit details.
What does not come back is the person. Owner personal details are masked, deliberately, and any service claiming to return a name, phone number or address from a plate is either misrepresenting what it does or should not be doing it. Treat that as a signal about the vendor.
For a fleet this is the right trade. You are confirming a vehicle is legal to load, not building a file on its owner. See what Vahan is.