/Library/LaunchDaemons/local.time-sync.plist (Cron for syncing time every 1200 seconds on macOS)

local.time-sync.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
  <dict>
    <key>Label</key>
    <string>local.time-sync</string>

    <key>ProgramArguments</key>
    <array>
      <string>ntpdate</string>
      <string>-s</string>
      <string>-u</string>
      <string>0.cn.pool.ntp.org</string>
      <string>1.cn.pool.ntp.org</string>
      <string>2.cn.pool.ntp.org</string>
      <string>3.cn.pool.ntp.org</string>
      <string>time.apple.com</string>
    </array>

    <key>StartInterval</key>
    <integer>1200</integer>

    <key>RunAtLoad</key>
    <true/>

  </dict>
</plist>