OnePlus
Add an Alternate Calendar to the Calendar App auf OnePlus
The Calendar app on OnePlus phones shows only the default Gregorian dates unless you turn on a second date system. This is useful if you follow religious or cultural dates alongside the standard calendar, for example for planning holidays or events tied to another calendar system.
The setting adds the alternate dates in smaller text under the main date grid. It does not replace the default calendar and does not change how existing events or reminders are stored.
Where to find the setting
Open the path Open the Calendar app ➔ Open the menu ➔ Open the Settings ➔ Tap on General ➔ Tap on Alternate calendar ➔ Choose an alternate calendar.
Available options are Chinese calendar, Simplified Chinese calendar, Traditional, Hebrew and Hijri. Pick the one you need and return to the main calendar view to see the extra dates appear.
If you later want to go back to only the Gregorian view, repeat the same path and select the option to turn the alternate calendar off again.