The Sent folder is within the closed folder More at the bottom after the other built-in folders Inbox, … etc.
To get to the sent messages and see them one has to open the More folder.
I have not found a configuration choice to get Sent on the list with Inbox etc.
In terms of space there is no reason Sent should be “hidden” within in a separate More folder.
Please advice how to get rid of the More folder so Sent is shown with the others.
(Note that the folders have norwegian names, i.e. Sendt (for Sent) and Mer (for More)).