Select a message and look at the row of icons above it (reply, forward, etc) The last one is 'more'. Click that and then click customize. That menu shows the option to show photos.

David... Ok, thanks!...so I see how that works for the individual message reading pane. But how do I get them to display in the inbox message list section (next to the sender somewhere)?? Yeah, sure, I like/want them in the message reading pane, too. But seeing them in the inbox list helps me identify the sender quicker. (I get A LOT of email 😂)

I am not aware of any way to do that.