Large Dark Spot on Arhaus Leather Sofa

[ahiestand]

Hi! First time poster. This site has come up a lot in my Google searches, so I am posting to see if you can send me in the right direction!

I just purchased this Arhaus leather sofa secondhand. This is my first time owning a decent leather sofa, so I am unsure of how to care for it or how to treat the dark stains. One of the dark spots is rather large. I've tried searching how to clean the dark stain, but I don't know what caused the stain (i.e., is it protein-based, oil/grease, etc?), so I'm left wondering what would be the best approach...or if I should accept it as it is and let my three kids continue the destruction.

I'm also looking for input about how I can care for the sofa in general.

Thank you!