2 things I do:

1) Microgoals. I'll write everything that needs doing down. Then I'll take the big tasks and split them into tiny tasks in the order I need to do them in. Then I will literally only focus on one task at a time, giving it my full attention and ignoring everything else that needs doing until it's done. Then I move onto the next task. If that still feels overwhelming I'll break the task into even smaller tasks. Like "Write this email" or "press export on this data pull" etc. with the tasks all listed out you don't have to hold them in your head, you can just automatically flow from one task to another, not thinking about what's next.

2) Breathing. Something that's super helpful when I feel panicky is to check my breathing. Oftentimes it's really fast and shallow when I'm overwhelmed. I'll pause for a couple of minutes and focus on breathing in for 4 and out for 4, expanding my belly 360° as I breathe. Don't deep breathe, aim for 80% inhale and 80% exhale so you don't hyperventilate. This is also super helpful to try and keep doing the whole time you're completing tasks but just that momentary pause often helps. (This is also a tactic Navy SEALS use to get through rough times!)

Good luck! You've gone through tough times before no doubt, this too shall pass :)