You would like to be able to notify L2 and L3 Managers in Opportunities via Workflow Rule.
SAP Cloud for Customer
Unfortunately, the recipients "2rd Level Reporting Line Manager" and "3rd Level Reporting Line Manager" (as for instance for Sales Quotes) are not available for Opportunities.
This is the current expected behavior of SAP Cloud for Customer.
As a workaround, you could define Workflow Rules for Z-party Role Recipients and populate the L2, L3 manager via PDI with those z-party roles in the Opportunities.
Notification, E-mail, Workflow Rule, Managers, Opportunities , KBA , LOD-CRM-OPP , Opportunity Management , How To
SAP Cloud for Customer add-ins all versions ; SAP Cloud for Customer core applications all versions