I have two users in Taipei time zone.
Both are using PCs with system time correctly set to Taipei time.
Both have an Office 365 E3 Enterprise account on the same tenant and have Office 2016 installed.
Both use Outlook 2016 for their email needs and connect to the same on-premises Exchange server.
For one user, all time stamps on email display correctly with Taipei time.
For the other user, all time stamps on email seem to be using PST time.
Everything I google seems to reference time zones in Outlook's calendar functions, but they don't even use their calendars. This is only in reference to the email time stamps.