In Modern Ux, Weekly Period Type is not available while creating/updating Cost Plans, however, you get to choose Per-Period metrics (TSVs) to be viewed by any time period type (Monthly/Quarterly/Annually) including weekly
STEPS TO REPRODUCE:
Expected Results: User should be able to select weekly period during creation/editing of cost plan
Actual Results: User doesn't have option to select weekly period type
Release : 15.9.3,16.0.0
Component : CLARITY STUDIO
This is a defect DE63345
The defect DE63345 is fixed in 16.0.1