You can make all the cards in the gallery have the same size by setting a fixed height for each field. You can adjust the field height by clicking on the field name on the extension settings page.

The only way to make the gallery cards have the same height is by setting a fixed height for each field. It's not possible to adjust the field heights automatically based on the highest field.

Also, you would need to set a fixed height for the cover image too. Go to: