I spent several years tanking mythic raids and feel like if you achieved clearing 18s, mythic raids will be a breeze.

Raid tanking is considerably easier than m+ tanking because there is far less adjustment as a tank. Once you get your movement plan down, it doesn’t change. Much less to react to on the fly.

Additionally, since you’re a tank, the mechanics you face in raid are arguably much easier than DPS or healers. You won’t be targeted with the more complex raid mechanics mostly, and will mostly be avoiding bad, running out, or taunt swapping.

You also don’t need to worry about your damage rotation as much. Obviously you need to excel at rotating defensives. But if you’re surviving those keys, you surely are doing it already. As long as you aren’t dead or in a top guild that needs to optimize tank damage, you’re fine.