I think that if Nintendo ever developed and made a original survival horror IP BY THEMSELVES (not published nor collabbed and it isn’t Luigi Mansion), I think they would be do something like this (edited image for illustrative proposes)

I think would feature a Cute, child-friendly mascot character who goes through the most horrifying world and setting possible but genuinely dosen't get scared by it, done in a way that makes people playing both eased by the character and his humorous reactions but uneased due of knowing and genuinely terrified as the player knows the disturbing things that the character doesn't seems to care.

I think they would also use very universal fears, possibly of protection and seeing someone getting in danger whether that it is a plushie for a young child or child themselves for a parent