If phones normally receive say 2 years of updates, any phone built since 2016 - thus eol in 2023, should support it (chrome/firefox were supporting tls 1.3 in 2017) - i.e in the next 18 months.

A vulnerability in TLS1.2 would need to be fixed (by implementing TLS1.3) in 7 years under "security patching".

One thing, sometimes phones are released, but manufactured for 2 or 3 years, plus sit on store shelves for a year after that.

Today, you can often find such new phones on sale, yet already? No security updates. End of support.

So the life of a phone model before you even buy it new, may be years...