No, there is no way to add new value to as existing selection field (created by python) without python code.
Selection field selection values don't store in a database. when the server start its create python instance of the field class and for selection value stored in the instance.
That's why we don't change it from UI/Settings (unlike other attributes of fields).
due to this limitation odoo studio could not provide an option to add value to selection field

It is possible for Custom Fields, either through Odoo Studio or through Settings / Technical / Fields, but not for base fields.