drop down menu with option to add values to the list w/ new entry

[OS]

I am trying to design a table with a field that has a drop down menu. I want
to have the option that if a user can't see the desired value listed in the
drop down menu, they can add it manually (won't select any value from the
list), but that new added value will be automatically added to the original
list so that next time a user is about to fill out the table, the new value
will be listed as part of the options in the drop down menu. (basically the
original list with the values for the drop down menu can expand with each new
entry added to the list). Is it even possible in Excel? Thanks.