My JEE Mains score is low, but I may score good in class 12th. Can you suggest some reputed colleges with good ranking?

Some reputed BTech colleges in India do have admissions with lower JEE Main scores.

You could target Centrally-Funded Technical Institutes (CFTIs), possibly some newer NITs, and Indian Institutes of Information Technology (IIITs) that accept closing ranks of around 326262 or similar. Examples include

Shastra University best for placement and good B.Tech college

Birla Institute of Technology and Science (BITS Pilani)

NIRF: Top private college

Avg package: ₹20L+ 

Admission: BITSAT (no JEE needed)

 Only if you prepare seriously for BITSAT