No, there is no setting or feature parameter required to support the multi-picklist field. You just need to add field mapping for the picklist field on the Field Mapping screen and give read/edit access to that field in the public access settings of the site.
- If you want to add a multi-picklist field on the Account Update Form, please follow these steps: https://satrangtech.freshdesk.com/support/solutions/articles/17000084835
- If you want to add a multi-picklist field on the Contact Update Form, please follow these steps: https://satrangtech.freshdesk.com/support/solutions/articles/17000084836
- If you want to add a multi-picklist field on the Lead Update Form, please follow these steps: https://satrangtech.freshdesk.com/support/solutions/articles/17000122993