If you want to exclude certain products from being reviewed or exclude sending review requests to specific customers, go to the Exclusion Filters in the Configuration.
If you want to exclude review requests across the board on your website - including not showing the “write review” link in the widgets - go to the Exclusion Filters.
Go to Configuration → Exclusion Filters
There are multiple product or customer attributes that can be used for exclusions.
Product attributes:
ID
tags
c. name/title
d. category/collection
2. Customer attributes:
a. country
b. email
c. tags
d. notes
Here is a video on how to do a product exclusion in your store: