Giving People Managers Permission to Manage Their People's Projects

Our group is scaling to include more managers of individuals. They are eager to participate in adjusting assignments and planned dates on behalf of their resources. Is there an easy way to give a resource's manager Manage rights to their project or task? I have been looking for a checkbox or toggle...

Right now our options include:

• Assigning tasks/projects to the manager first (too manual)
• Having individuals share projects one by one with their managers (too manual)
• Putting all of the managers on a team that gives them Manage access to all projects (too broad)
• Making some kind of change to a system-wide access level (way too broad)

Hoping for some other ideas! Or validation that there isn't an easy setting to accomplish this.