There are a huge amount of addons that can be important to help with Tanking. These are just a few suggestions of addons used by me, but feel free to look for alternative addons that do a similar job if my choices are not what you are looking for.
For a direct source to ESO Addons check out ESOUI.com
You can also use Minion which is a program that basically does all the work for you, all you do is browse the listed addons and install them and it sorts everything for you. Check out Minion for that.
Some of the addons I use are custom built addons that are made by people and then not imported onto ESOUI, the only way to get these would be to ask for them on The Tank Club Discord.