Enable Sync in Google Calendar App Settings

How to enable Sync in the Google Calendar App for calendars that don't appear in the main app menu, but work normally in a browser.

Our Advanced Calendar Tools:

Sheets2GCal (Sheets add-on)
Sheets2GCal is designed for advanced Google Calendar management using spreadsheets. Create or import events in a spreadsheet, edit them in the Sheet and export the changes to Google Calendar, or edit them in Google Calendar and import the changes back to Google Sheets.

GCalToolkit (Desktop software)

GCalExtras (Calendar add-on)
GCalExtras integrates with Google Calendar to provide extra functionality such as saving/loading groups of calendars, mass copy/edit for a range of events, easy access to the event location text, and storing private notes associated with individual events.

[Lockkjaw]

How do I add more categories in google calendar mobile.?

[zairulfiras]

How do I add the colour tag and its name? Please teach me

[bl]

bro why do i not get the show more option