To share your outlook calendar please follow these steps on Classic Outlook:
From your Calendar folder, on the Home tab, select Share Calendar.
From the drop-down menu, choose the calendar you want to share.
In the Calendar Properties dialog box, select Add. (Please see below to read about the permissions that are available to you)
You can search for people from your address book or type in their email addresses in the Add box. When you're done adding names in the Add Users dialog box, select OK.
Back in the Calendar Properties dialog box, select the person's name or email address, then choose the level of details that you want to share with the person, then select OK. When sharing your calendar, you can choose from several different permission levels:
Can view when I'm busy. Those sharing your calendar with this permission level can only see which times you're available.
Can view titles and locations. Those sharing your calendar with this permission level will see availability and the subject and meeting location.
Can view all details. Those sharing your calendar with this permission level will see all details of your appointments, just like what you see.
Note: If you see a message that says This calendar can't be shared, there are three possible reasons:
The email address is invalid.
The email address is a Microsoft 365 Group
The email address belongs to an external user who isn't part of your organization.
The person you've shared your calendar with will receive a sharing invitation by email.
Once the recipient selects Accept, they'll see your shared calendar in their calendar list.