You can set a question to be optional when creating during creation. Optional questions are not required to be completed by the reviewee to submit their review.
Create an optional question
Option 1: Create a question from the Question Bank
Step 1: Navigate to Admin > Reviews > Questions.
Step 2: Click Create question to bring up the editing modal.
Option 2: Create a question from a review template
Step 1: Navigate to Admin > Reviews > Templates > Create new template.
Step 2: Click + Create question to bring up the editing modal.
Making an entire or part of a question optional
To make a response type optional, click on the Optional checkbox next to each response type.

How do optional questions appear in a review?
Optional questions will appear without a red asterisk and the word Optional under the question when a reviewer responds to the question in a review cycle. Hovering over the icon informs the reviewer that only the manager and the admin will view the response, not the reviewee.

Please note: The reviewee's review packet does not indicate whether the question they answered was optional or required.