To view room calendars in Outlook, you will add the room calendar to your calendars listing, which will allow you to quickly turn a room calendar view on or off, or overlay it to your own calendar. This is similar to viewing an individual calendar that a colleague has shared with you.
Please see the appropriate section below for viewing a room calendar using the Outlook desktop client (on your local Windows laptop, for example), or using the Outlook web client (https://outlook.office.com/).