How to create a new activity in monday.com with GraphQL query

Hello,

I had a question regarding Monday GraphQL query option. I have a board with items, and in an item I want to add a new activity (which can manually be done in the upper left:

However, I am not sure if that is possible via GraphQL query. Could someone help me with how to do that and what query should I use? Adding a new “subitem” doesn’t work.

Thanks in advance!
Tara