Open https://time.is/ in a browser
If your clock is not in sync you will see the differential between the synchronization of your machine
Referenced from here.
On your Mac, choose Apple menu > System Preferences, then click Date & Time.
Click Date & Time, then set the date and time automatically or manually.
Click Time Zone, then set the time zone automatically or manually.
Referenced from here.
Open Control Panel.
Click on Clock, Language, and Region.
Click on Date and Time.
Click on the Internet Time tab.
Click the Change settings button.
Check that the Synchronize with an internet time server option is selected.
Use the drop-down menu to select a different server.
Click the Update now button to synchronize the time with the new server.
Click OK.
Click Apply.
Click OK.
Visit https://time.is/ again and you should see the message “Your time is exact!”