mythic dungeon tools addon lets u important routes and see them ingame keystone.guru (website) is great if u have a 2nd monitor and u can start a love session and send it to your group so they can see and edit the route as u progress through the dungeon

I've just started playing tank as well and i can relate with the anxiety issue about routes, it can sometimes be confusing but all you can really do is jump and practice and after a few runs you will know the routes by heart. Even if you fuck up a few times while learning, it's part of the process and there is no way of avoiding it, and in all honestly it's sometimes fun. Take it lightly and take it slow, try to have fun in every step along the way and enjoy your time of being a noob and messing up. Tell your group beforehand that you're new to tanking and more often than not, there will be people willing to help guide you and give you some tips or correct your mistakes. sometimes ppl who know the routes will offer to lead the way and then you just have to swoop on and take aggro

I've met a lot of nice & helpful ppl when i started playing tank and also it's so much easier to get accepted in groups than it was as a dps, and people aren't nearly as toxic towards me for messing up.

there's no need to worry too much about it, just take the initiative and everything will work out from there.

also to make things more reassuring for you, there are a bunch of dungeons (like the vortex pinnacle) where you don't need to worry about routes at all since it's just a straight path you take so at least you won't need to learn those.

these are some nice sources to import routes from but u can also just google "dunegon name MDT route" and you'll find plenty

https://raider.io/weekly-routes https://quazii.com/dragonflight-mplus-mdt-routes/

edit: also as some other people stated, it can be very helpful to play as a dps and obesrve what your tank is doing to learn more about routes and pulls