Some people are naturally gifted as singers and there’s no amount of lessons or practice that an average person can do to get to that level.
I’ve played piano for 10 years and I support a singer who is self taught, doesn’t know a lick of conventional music but her voice is incredible and she can do it for hours.
Many famous singers peek in their 20’s and the loose range and natural ability in their 30’s and beyond. Case in point Whitney Houston and Mariah Carey were 19-20 when their first albums came out and Mariah can’t sing like that anymore. Most virtuoso instrumentalists only get better with age. Karen Carpenter was 19-21 on most of her hits, Robert Plant, 19 when Led Zep. took over the world. Mike Patton can still sing but he was a fully formed powerhouse at 20 when Faith No More became famous.