This is another exciting feature that Dynamics 365 CE has introduced. Here, we can create a multi-select option field by setting the data type to MultiSelect Option Set in the new field creation window. Once a field has been created, we can see the multi-select options, as shown in the following screenshot:
After selecting each option, they will be displayed in the text field, as shown in the preceding screenshot. When you close the tab, the values will be separated by a semicolon. This field is available for both new Unified Interface apps and the web client. This field can be added to a variety of forms, such as the quick create form, main form, and quick view form, as well as on views.