Iphone X calendar subscriptions

To subscribe to a calendar go to Passwords & Accounts. Tap on Add Account, then Other, then Add Subscribed Calendar. You will need to know the url of the calendar you want to subscribe to.

For a much easier way, first find the website that hosts the calendar using Safari on your phone. Select the calendar you want, and there should be a "Subscribe" button next to it.

Open the calendar app and one the bottom middle you will see "calendar" select that and you can tap on the calendar you want to unsubscribe from.