If the fm radio chip isn't enabled on the phone in question, it can't be done.

it worked fine till it upgraded to android 11,then it stopped working

What phone do you have?

Samsung s10 

I’m not sure if this will work, but one comment in the review section of the Next Radio app on Google Play mentions not to enable location and instead of selecting a country select ‘other’ and this should get you to the FM radio section. 

NextRadio Free Live FM Radio

i tryed that ,still not working, i think you have to hack the phone, to give the proper permisions

Are other people reporting the same issue with the same phone? 

Seems  like any phone  running Android 11 ,they stopped the next radio app  from getting access to the fm chip

It does not seem like the developer made any changes with the update. I’m afraid you are out of luck on that. https://forums.androidcentral.com/samsung-galaxy-s10e/1021482-if-you-use-nextradio-dont-update-android-11-a.html

Seems there are some other reasons why NextRadio is no longer.

https://radioink.com/2018/10/11/emmis-pulling-the-plug-on-nextradio/

looks like no more offline radio on newer phones ,unless some one can figer out how to access the fm chip

A different scenario with Mr. Reid. Sadly, Spirit1 & 2 (FM radio) went the same route.

https://forum.xda-developers.com/t/spirit1-spirit2-real-fm-radio-general-thread.1059296/

Pretty sure jailbreaking might have something to reactivate it but most likely will void the warranty