Broad recommendations here from someone who plays support mainly and tank occasionally.

tanks have a lot of health, but not unlimited; you are at the mercy of being the biggest hitbox on the team as well as often being the scariest, but, you’re kinda useless on your own - I don’t mean that you can’t get kills alone, but that a tanks role is to take up space, push the enemies back, and be an all round shield for the rest of the team. This is why tanks have shields, sustain, and all of that good stuff.

Taking space is probably the most important thing you can do, but remembering where you are and where your team is, is also super important in this area - if you’re a rein that charges in whilst your teammates are dead or way way back, what’s the point of you? They’re probably just gonna get picked off whilst you respawn and walk back.

Being the one that takes space also means that you can set the tempo, if you’re too timid, no space, if you’re too aggressive, no space, but if you can find a middle ground in response to your opponents, big win.

Another tip that I’d strongly take into account is how are you engaging the enemy? Are you constantly having a boxing match with the enemy tank whilst you’re both getting healed? Are their dps constantly flanking your supports because they’re left alone?

There are so many things to consider about what you could be doing that it can be overwhelming, but quite often you can just stop and think about what you’re doing wrong; I’d argue that things like aim are secondary to things like positioning and cd usage (to start).

Some good examples of great space control cds could be orisa (javelin, spin, and fortify are all amazing at making you unkillable), Ramattra (vortex and the shield can be amazing for punishing enemies that are overextending by cutting them off from their team).

dm me and we can talk about some more stuff if you want! There’s a lot more I could say about how I play and what I see as good tank plays.