It's difficult to put into a single genre but it's not yaoi. It kind of switches between two timeline (debatable if they even play in the same universe). One timeline is about the mafia boss adopting a little boy and it is mostly about their experiences so probably slice of life. There are occasionally hints on romantic feeling between two of the subordinants but nothing explicit.
In the second timeline the little kid is older - maybe 20ish- und he does have feelings for the mafia boss but also nothing explicit

Is this yaoi.? I see a lot on insta about this. Is it yaoi?