There are three options for you to share the sublist with: Project Members, External Team and Personal (yourself).
Learn how to create a sublist.
Share sublist with project members
The newly created sublist will be visible to all of the project members (excluding the External Team). There’s no way to customize to selected project members.
Share sublist with external team
All of the members in External Team can view the tasks within in this sublist. If you add a task in this sublist, it is automatically assigned to the External Team.
However, if you add a parent task with an already assigned subtask to this sublist, the subtask will not be reassigned to the External Team.
Create a personal sublist
The newly created sublist will be visible to you only. Other project members cannot view or edit the sublist even with the shared link.