Auto create table option will create table with default data types. You will have to alter the table later and modify data types as required.
If you are concerned about table definition, better to create the table in advance.
See similar question - https://stackoverflow.com/questions/61240726/why-the-default-auto-created-sql-tables-column-length-is-1-in-azure-data-factor
Please don't forget to Accept Answer and Up-vote if the response helped -- Vaibhav