
Ghost of Yotei developer Sucker Punch wasn't trying to make a longer game than Ghost of Tsushima - they just wanted to improve the original game's "sense of grandness and scale."
Regardless of the developer's intention, Sucker Punch co-founder Brian Fleming told Game File (paywalled) it should take you "a little bit longer" to beat Ghost of Yotei than Ghost of Tsushima, but adding length to the sequel's main quest wasn't the main intention.