Check thishttps://m.economictimes.com/news/new-updates/jio-5g-welcome-offer-heres-how-to-sign-up-and-use-5g-on-your-phone/articleshow/96218117.cmsThe important thing is that you must have an active plan of 239 rupees or higher.
To use Jio True 5g, first you have to register for "jio welcome offer," which gives you unlimited 5g data .After registration, you will receive an invitation with a week.Then you can use jio True 5g.