If you are using the Call REST action, then in the Response tab there is an option to Commit the response. This will store the response in the Mendix database.
If you want more flexibility you can manipulate the List in the calling Microflow before committing the data using a Commit action or a Change action with commit selected.
Hope this helps.
In your Rest Call action, you can configure to apply an Import Mapping. There, you can also choose the commit behavior of the mapping: you can choose to either commit, commit without events, or not commit imported objects.
If you want to commit only specific parts of the result (or just have a bit more flexibility), you can also not commit and store the result in a variable (which likely has a root with the list associated with it). Then, you can retrieve the list of objects attached to the Root (with a normal retrieve action) and commit that.
Some more information can be found here: