Dear Mary Lynn Banchoff,
Good day! Many thanks for your reply and information provided.
I have been researching on this, and based on my research, I got the same result as yours, there is currently no way to search “all outlook items” in Outlook on the Web and New Outlook. We apologize if we are not able to meet your requirements now; however, thank you for bringing this to our attention, we will surely raise your concerns to our Product Team and hopefully this can be considered in the future updates.
To get back this feature more quickly, I made an entry as a feature request in feedback collection here >>> Add back the search “all outlook items” in Outlook on the Web and New Outlook · Community (microsoft.com) and many other users requested the same, like in Bring back search in All Outlook Items and All Mailboxes · Community (microsoft.com) and New Outlook: Cant Search ALL MAIL ITEMS · Community (microsoft.com). Please add your vote and comment and other users may vote it as well and make this more visible to the service team so that it may be considered for future upgrades. We also invite you to vote the reply here to make this thread a top content so that others may find it easier.
I will update here if I get any useful update on this feature. Thank you for your understanding and support.
For other concerns, please do not hesitate to add you post in the Microsoft Community Team.