One country took on the world’s biggest commercial landlord
theguardian.comIf you read the article, it says they didn't do Anything except force them to do energy efficient and safe housing upgrades. So Denmark actually failed.
I'm not sure that summary is quite correct.
Looks like they passed a law designed to curtail speculation and rapid price hikes throughout the country. It says landlords cannot raise rent on apartments they renovated for 5 years after they purchased them. They must increase energy efficiency too. Finally, they cannot pay tenants money to leave.
Maybe it will help some. Time will tell.