Hey aspirant,

Most NITs allow branch change. Some of the NITs which allow branch change are NITK Surathkal, NIT Warangal, NIT Calicut, NIT Patna, NIT Silchar, VNIT Nagpur etc. But branch change is usually not easy. First of all, you must score a very high GPA, usually 9.5-9.8 and above (depends on each institute). There also must be a vacancy in a branch you want to change or upgrade to. Usually branches like CSE are full and chances of vacancy are rare.

Hope it helps. All the best!