Is it possible to put a link to data in another data in Firebase?

Question

Database

Hi all.
I decided to try to make an MVP for practice and training for, let's say, a "local interest club". And the question was how to implement something similar to "many to many" in a noSQL database?
Is it possible to do something like this:

-some data
--data elem 1
 --elem prop 1
 --elem prop 2
 --another elem prop 3
--data elem 2
--data elem 3


-another data
--another data elem 1
 --another elem prop 1
 --another elem prop 2
 --another elem prop 3
--another data elem 2
--another data elem 3

Or tell me the practice of implementing similar tasks in other noSQL databases.