1. Go to Extend and install the Configuration Translation module. It will prompt you to enable the Interface Translation, Language, File, and Field modules to be installed, if they are not.
2. After the module is installed, go to Configuration. Then, go to the Configuration translation page under the Regional and Language section.

 

3. Click on the list for the Date format option in the configuration entity option table:

4. We will translate the Default long date format to represent the Danish format. Click on the Translate for the Default long date format row.
5. Click on Add to create a Danish translation:

6. For Danish, we will provide the following PHP date format: l j. F, Y - H.i. This will display the day of the week, the day of the month, the month, the full year, and the 24-hour notation for the time.

 

7. Click on Save translation.
8. Whenever a user is browsing your Drupal site with Danish as their language, the date format will now be localized for their experience.