Hi Shruthi,
Could you please elaborate the question, So that I can explain.
Hey Sruthi,
You can perform a change List activity to add objects to your list. Is not possible to add string alone, I mean, without any object because a List should have a specific return type.
Then if you want to have the values on a specific order, you can use the list operation activity to Sort the list .
Check this doc to have more information related with the lists behaviour: https://docs.mendix.com/refguide/working-with-lists-in-a-microflow/
If this answer helped, mark as "accepted"
Best Regards,
Ricardo Pereira