I do have VoLTE enabled in Settings, LTE is selected (I'm usually on band 4 or 12) but I don't see what Samsung calls a "IMS Network Status Indicator" - I expect it is a "HD+" icon.
Also, I have never seen a wideband codec in use, just AMR NB while on calls to other mobiles that support VoLTE.
My old Mate 20 pro has always shown an HD icon.
EDIT : I ran a quick test, with VOLTE enabled, data stays on LTE, without it, it drops to 4G. So it VoLTE works, it's just the indicator missing.
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