It can be taught!
I can play instruments but never thought I could sing outside a range of less than an octave in the baritone range.
When I was 50 we had a singing teacher over at our house for my children. I asked if she could help my range. That day she took my voice to a high C. I am actually a tenor and can sing pretty much all the high parts. I am my in-laws’ favorite opera singer now.
Also I was too timid. Singing is really just controlled shouting.
I hear you. At 49 I also discovered an extra octave up there above the high e. Also baritone. The YouTube singiverse did it for me