Collection templates in Keystone are compatible with Shopify's official Search & Discovery app. This app can be used to customize and extend the available filters for your store.
Enable collection filters
Go to Online Store > Themes > Customize
From the dropdown in the center of the top bar select Collections > Default collection
On the left hand side, select Collection grid in the theme sections
Scroll down under Display and check Enable filter
Enable collection sorting
Go to Online Store > Themes > Customize
From the dropdown in the center of the top bar select Collections > Default collection
On the left hand side, select Collection grid in the theme sections