There are manual product review links that you can send customers for them to review a particular product, and the same goes for site reviews. These are best used on a one-off basis when you want to reach out to a customer (or you're already chatting with them) and they're interested in leaving a site review.
As a reminder: site reviews are a review of the overall shopping experience, they are not connected to a product, and they can be shown on-site using a review section.
To put together your manual site review link, go to your Store settings and under "Store health" you'll find your store key.
Copy the store key and add it to the url below by replacing "example-key" after the =
Now you're all set - paste that link into a browser (and share it with your customers) for them to leave you a site review :)