There are two ways to make an image clickable.
Make an image clickable
You can make an image clickable by adding a URL to the caption in Notion.
Make a gallery item click through to external site
You can make a gallery item click through an external URL
Add a URL property called
super:Linkto the database
Add URLs to the database pages that you want to click through to the URL
Edit the gallery view in Notion and show this property on the cover of the gallery view.