If you are permanently going to stay in india you can check this on xda developer website you will find the solution but its more technical so if you are tech savy you can do it, if you are here temporarily i would suggest dont do it or you can also ...

This is a known issue for devices from US , Canada as they dont have stand alone band enabled , did you get one ui 6 update?

Its on the 5g technology airtel uses non stand alone..while jio uses stand alone bands..thats y the call it true 5g

This is the post

https://r2.community.samsung.com/t5/Galaxy-S/5G-working-after-One-UI-6-update-for-UK-Variant-Phones-also/td-p/14916171?src=ShareByUserCM