Create a Multi-Level Cascading Select field (Cloud)
This is how to create a Multi-Level Cascade Select custom field:
Go to Settings → Work items.
Go to Fields → Create new field.
While finding the field type, click on “My field type isn’t listed here” and select “use the old field creation experience.“
Click on Create custom field.
Find Multi-Level Cascade Select (multiple selects) in the Advanced list.
Set a name and, optionally, a description for the new field.
Choose the screens and contexts where you want to associate the Multi-Level Cascade Select custom field.
MLCS is now ready to use.