Many selects
This module improves how administrators manage select fields that allow multiple selections. It offers a better widget for these fields, making it easier and faster for content managers to add options to list fields.
The Many Selects module enhances the administration experience on work with select field types when a multiple selection is required. This provides a better Widget for select field type that allows a content manager to have an easier and faster way to add desired options for the list field. Drupal 8 Actively maintained version of Drupal 7 Multiple selects module.
INSTALLATION
Install as you would normally install a contributed Drupal module. Visit:
https://www.drupal.org/docs/8/extending-drupal-8/installing-drupal-8-modules
for further information.
HOW TO USE
Go to Entity Form Display and select "Many select list(s)", configure it.
MODULE CONFIGURATION
No configs required.