@Orsini, Patricia (she/her) said
I have new outlook and can not longer sort by subject
When you are looking at your message list, if you click on the "By Date" in the upper right, you should see this and be able to choose "Subject". Do you not see the same?
But what you are not going to like is that
this also causes Outlook to "Group By" subject, so that there is a separator between different Subjects that you can not remove.
You can Vote for an comment on this Feature Request to help convince Microsoft to allow Sorting without Grouping.
https://feedbackportal.microsoft.com/feedback/idea/27de2f9f-3cfa-f011-bb46-7c1e529117fa
(You must "Sign In" at the top right of the Feedback page before you can vote).