I’ve been working across four different time zones in the last fortnight and one of the cool things about most modern operating systems is that your device automatically updates based on the IP address of the internet connection.
Therefore, when I left Auckland and arrived in Bangkok, my Surface Laptop automatically changed to UTC +07:00 (6hrs behind NZ currently). When I moved on to Singapore (UTC +08:00) Outlook automatically updated accordingly, however when I tried to set a calendar appointment with a school back in NZ the invite ended up being 8pm NZ time because Outlook was showing me local times automatically.
I was chatting about this with my colleague Amit Pawar when we were in Indonesia today (back to UTC +07:00) and he pointed out a great feature in Outlook Calendar settings that allows you to align up to three different time zones down the left:

Note the column headings showing SG (Singapore) NZ (New Zealand) and “Current” – the automatic time zone setting based on my current location.
When I return to NZ I’ll likely swap out the NZ time zone option and replace it with Pacific Standard Time given the communications I often have with the team at Redmond in Seattle.
Instructions for setting additional time zones
The additional time zone settings can be configured under the Calendar Options in Outlook:
Small features like this are often overlooked among the myriad of settings that large applications like Outlook contain, however they can add significant value and help avoid mistakes like sending meeting invites for 8pm in a different time zone!
Here we are, March 2023. I only learnt of this feature in Jan 2023 – a bit over 4 years after your post. It’s neat. However… I want FOUR timezones in that interface! Some users are never happy, eh?
Ha! Glad you found it and sure, why not four!