OnePlus
Show or Hide Calendar Week Number auf OnePlus
The OnePlus Calendar app hides week numbers by default, and this is a setting inside the app itself, not a system-wide Android option.
Because the option lives in the app's own preferences, changing it only affects the built-in Calendar app. If you rely on Google Calendar or another calendar app instead, you need to look for a similar setting there.
To switch week numbers on or off, go to Open the Calendar app ➔ Open the menu ➔ Open the Settings ➔ Tap on General ➔ Enable or disable Show week number.
Once enabled, a small number appears next to every week row in month view, matching the standard ISO week count most work calendars use for planning. This makes it easier to reference a specific week during scheduling without doing the math yourself.
Turning the option off removes the numbers again and gives the date grid slightly more room, which can look cleaner if you never reference week numbers.