I'm not sure I can do this again.

[Kyuuen]

WoW's expansions are vastly different from one another with whole new ways of playing each time.

As someone who still occasionally plays WoW; no it has not.

The only things WoW can attest to doing differently are special random BG's; one per week, (Snow Blind (Arathi Basin), Gravity loss/Lapse (Storm's Eye?)) and battlegrounds like them and Mythic keystones which changes certain stat variables for a given dungeon run, in which both of those were added in Legion. The last thing they added to the game which changed things up were open world Battleground PvP zones (Winter Grasp and the failed monstrosity from WoD). And I suppose pet battles, if you find that interesting. And I forgot the artifact/relic weapon system for Legion, but that's gone come next x-pac.

The leveling formula is largely unchanged.
The dungeon formula is largely unchanged.
The raiding formula is largely unchanged.
The PvP formula is largely unchanged.
Crafting/gathering is largely unchanged.

The only thing that really changes are the themes of the expansion.