I have manually entered section titles in a manuscript (screenshot 1) and created a TOC (screenshot 2). The setup is shown in screenshot #3. The page-number alignment with leader dots is good, but I can't figure out how to right-align the section numbers to the left of each entry. I have seen several threads about aligning numbers in TOCs, but can't locate anything that addresses this. The only workaround seems to be to manually put a space before each section title from 5.1 through 5.9, but there must be a better way. Thanks for any assistance.
I have manually entered section titles in a manuscript (screenshot 1)
You manually entered the section titles, but did you manually add the numbers, or are you using auto-numbers?
If you are using auto-numbers, you should be able to exclude them from the TOC (it is in the last menu at the bottom of your third screen shot), and the add them back in with the TOC paragraph style—Topic Title-Pickup for TOC—to match the book numbers. Then use the right-alignment option for the numbers. Play with the left indent until you get the look you are after.