Force enable VoLTE/VoWiFi on rooted Androids

Notes:
- Make sure that your service provider supports VoLTE/VoWiFi & enabled VoLTE/VoWiFi support for your account.
- Make sure that your device & device software supports VoLTE/WoWiFi in first place.
- Some devices may need more than just this in order to work (eg. Sony Xperia/OnePlus)

Method #1:
1. Add this below line in build.prop (located in /system/). You can add this for example via SmartPack-Kernel Manager or any root-enabled text editor. Credit

# Debug Options
persist.dbg.ims_volte_enable=1 
persist.dbg.volte_avail_ovr=1 
persist.dbg.vt_avail_ovr=1
persist.dbg.wfc_avail_ovr=1

# Radio Options
persist.radio.rat_on=combine
persist.radio.data_ltd_sys_ind=1
persist.radio.data_con_rprt=1
persist.radio.calls.on.ims=1

2. Reboot.

Method #2 (easier):
1. Flash VoEnabler-1.8.zip from this XDA post via the Magisk Manager app (Hamburger menu > Modules > yellow Plus button) or recovery.

2. Reboot.