newmarket2, if you could each read your email in a web browser (or at least, one of you) and not use Office 365/Outlook, that would make things easier.
If you are only both needing separate email with Outlook, you could try to add the second email account on the first laptop and co-mingle that way. As long as you use IMAP for email not POP3, this will download and sync copies of the email on this laptop, but when other person gets home and uses their laptop, all of the email will show up there too once it is downloaded.
But, it would be cleaner for each person to have a separate account on the shared laptop - then login separately when each person is using it. It's easy to create a second login account on a Windows laptop. It's not quite like having a completely separate PC, but it's probably close enough for what you need.
Here's some info from Microsoft on how to create a second account on a PC:
https://support.microsoft.com/en-us/windows/add-or-remove-accounts-on-your-pc-104dc19f-6430-4b49-6a2b-e4dbd1dcdf32#:~:text=Select%20Start%20%3E%20Settings%20%3E%20Accounts%20%3E%20Other%20users%20(in%20some,type%2C%20and%20then%20select%20Add.