Many settings have changed in the transition from iPadOS14 to iPadOS15.
As you correctly observe, the previous Load Remote Images option (which should be disabled to prevent tracking - and reduce exposure to malicious content) - to replaced by three Privacy Protection settings:
You should still be able to download remote images for email, individually. For emails with embedded image content that has been blocked, you should see a Load All Images button at the top of the received email:
This arrangement allows you to review and assess an email - before downloading what may be unsafe content.