So I just got skyrim special edition recently, and one of the reasons why i got it was because of Heart-fire add on. So I am wondering, if I bought the house in Riften (I think its honeyside) would I be able to customize and furnish it so I can get children

The houses that you can buy in cities have nothing to do with Hearthfire.

They have pretty limited customization (you just pay for upgrades so the place feels less empty,) but you can adopt a child in them if you purchase the "Child's Bedroom" upgrade.



The three Hearthife homes are listed here: http://www.uesp.net/wiki/Skyrim:Hearthfire

These allow for greater customization on which types of rooms your house will have.