Just realized my alt is 28 necklace, while my main is only 30.
I do the same things on both: 4 WQs/day for emissary, 4 Islands/week for bonus, weekly guild raid, and a bit of M+.
My main has 7x the time played, but is only 2 levels ahead on neck.
I'd say Blizz did pretty good at making BfA alt-friendly.