The date/time module is default in the core and allows you to add a date/time field.

Unlike the Drupal 7 version you can not add start and end date/time in one field.

You can add a field 'date' to a contenttype.

date and time add new field.png

Set a default value if you want.

date and time default value.png

Set the fieldsettings

date and time field settings.png

The  display of the Date field can be set apart.  You can do this in 'Manage display' by the settingssymbol.

date and time tandwiel.png.

date and time keuzelijst dataformaten.png

or go to configuration - regional and language - date and time formats

date and time keuzelijst instellingen date and time format.png