Use APKPure App
Get 5G Only old version APK for Android
Change your network mode to 5G only (NR only)
You can now change the network mode of your mobile manually as you want.
There are many network modes that are hidden by the manufacture.
Such as
NR Only (5G Only)
LTE only (4G Only)
WCDMA only
GSM only ... etc
With this application, now you can access those modes.
What you have to do is only open the app