Make Your Custom Picklist Field Values Global #inSalesforce

To share the values with other objects, promote the picklist to a global value set.

Note: After a picklist is promoted to a global value set, you can’t demote it. 

Steps:

Go to the field of the object | click Edit | Click Promote to Global Value Set | Enter a label for the global value set | Accept the Field Name or edit it | Click Promote to Global Value Set

Considerations:

You can promote fields that have up to 1,000 values (both active and inactive).

You can promote only restricted picklists. To promote an unrestricted picklist, convert it to a restricted picklist.

and many more... Check reference

Reference:

https://help.salesforce.com/s/articleView?id=sf.fields_promote_picklists.htm&type=5