Well, in Germany at least - if the living space differs drastically, that is at least 10%, you can lower the rent accordingly and make a demand for a refund of the entire rent you overpaid since you moved in - and you probably should also make a second case for damages due to purposeful deception.

A consumer doesn't buy anything from a business "as seen", that is not a thing over here. There are binding rules to protect consumers from malevolent sellers or landlords, and legal obligations you can't subvert by tricking customers into purchasing something different from what was advertised.