Hey Biginner,
I'm not sure if I understood right, but you should do that in OutSystems.
Can you say what is your user case?
What you need to do?
It has lots of ways to do that, if you want to know if it is just logged you can see if the username Session/Client var is not empty for example:


This would be the simpler way I believe. But not so safe.
Another way is to check the UserId is not null also:

It is safer, but will go to the DataBase to check