To add shared calendars to your calendar view, follow the attached instructions at the bottom of this article.
And when creating Meeting Requests in Outlook, add your Attendees then click on the Scheduling Assistant option at the top, to see when all attendees would be available to pick the most opportune period for all.
When in Scheduling Assistant, you can then add or remove Required or Optional Attendees, and even select a Meeting Room.
This very short video (54 seconds) from Microsoft shows you exactly how; https://support.microsoft.com/en-us/office/create-appointments-and-meetings-in-outlook-6e6ddec6-5983-4c42-9652-b99e120206fb
Scheduling assistant in your mobile Outlook app
The scheduling assistant functionality is also available in the Outlook App for your mobile. 
Once in the Outlook app, tap on the + icon and select New Event.
Enter your meeting title and select your Attendees.
Then tap on the date or time, and you can start to view available options for all attendees;
The little colour-coded icon next to the attendee bubbles show whether they are available, as does the meeting slot you are creating.