The biggest dog I’ve ever met was a great dane that weighed 80kg (~176lbs). I’m short, but his back was on my waist-height, and his head was a lot bigger than mine. He was completely black too, so quite the startling sight running towards you, genuinely looked like some sort of hell hound lmao. He was very friendly though, we met him at a dog park. The owner also told me they had to order custom harnesses for him, since nothing commercially made was big enough