Now, to answer my own question: Referring to that attached screenshot, there is an arrow pointing to the button, just right of the Quick filter. That button will open a menu that provides display options. Select to sort by, then select Date at the top of the menu and Descending toward the bottom of the menu, fourth up from the bottom, in my case. The Descending option will put the newest email at the top.

Sounds like you are using the "cards view".

Personally I use the list view because it allows sorting on the fly because it has a message header to set the search item and show the default sort order of the folder. Note the direction of sort shown in the date column.

One day the card view might be good. Now it is not complete enough to entice me backwards. But I also do not try and fit the email content into a third colum on the right. I put it under the list ala Outlook Express and Eudora to name a few.

Linux_Mint_Firefox said

Now, to answer my own question: Referring to that attached screenshot, there is an arrow pointing to the button, just right of the Quick filter. That button will open a menu that provides display options. Select to sort by, then select Date at the top of the menu and Descending toward the bottom of the menu, fourth up from the bottom, in my case. The Descending option will put the newest email at the top.

Sounds like you are using the "cards view".

Personally I use the list view because it allows sorting on the fly because it has a message header to set the search item and show the default sort order of the folder. Note the direction of sort shown in the date column.

...

I am using the "Cards View." I had the list view on the earlier version of Thunderbird in my previous version of Linux Mint. Here, that's called "Table View." And it does have the message header's sorting abilities that I was familiar with.

I copied this title question's title from a DuckDuckGo search result and pasted it here, because that question was answered with how to do it the old way.  I've also discovered the answer in the documentation, I think in "What's new"  in TBird 115.