By default, all regional or national holidays are displayed in the calendar app of the OnePlus smartphone.

Depending on how many appointments or reminders are displayed for an account, the overview can quickly appear overloaded, which may lead to forgetting individual appointments or meetings.

In order to make the calendar view clearer, we can (de)activate the display of holidays at any time.

Android 10 | OxygenOS 10.0
Step 1:  Open the  Calendar app
Step 2:  Open the  menu
Step 3:  Enable or disable  Holidays
  1. Open the Calendar app
  2. Open the menu
  3. Enable or disable Holidays

OnePlus Instructions