A quick Google search for the keyword leads to dozens of piracy websites offering "480p, 720p, 1080p Hindi dubbed downloads." Here is why you should avoid them:
In some regions, you can buy seasons of Dark, but Hindi dubbing is rarely included in purchased versions. Always check the audio language list before buying. Dark Tv Series Hindi Dubbed Download
Illegal downloads often feature:
Executable files disguised as "Dark S01 Hindi dubbed.mp4.exe" are rampant. These contain ransomware, keyloggers, or crypto miners. A quick Google search for the keyword leads