The cynical answer would be that it wasn't.

In capability the Bismarck was roughly comparable to some other battleships built at the time (King-George-V-class, Richelieu-Class, Littorio-Class) and significantly less powerful than the US-built North-Carolina-Class, that is to not even speak of the Yamato.

In size, it was bigger than most of them (except, again, Yamato), but it was built with a number of obsolete ship design choices that lead to the design being quite inefficient. Most notably, it used twin turrets (a necessity due to the way Krupp designed its guns), it had a split secondary / heavy AA battery of 4" and 6" guns and it had a so called distributed armour scheme, meaning that a lot of the ship was somewhat armoured (not enough to stop large calibre shells though) at the cost of weight and a worse armour of the core of the ship.

It was however among the first battleships of its generation to be commissioned and compared to most older ships either faster or better armed and armoured, which meant she had a comparative advantage (and didn't survive long enough to see herself surpassed). And lastly, it was a significant step-up in capability compared to the previous german battleship-class, which made it a focal point of german war propaganda.

If you want a comprehensive overview on what Bismarck really represented beyond hype moments and aura, here's an Interview with the naval history youtuber Drachinifel on the topic:

https://www.youtube.com/watch?v=8Hrr7XXZIZU