1. To outlaw AirBnB. Except if people are staying in your house while you're there. Other than that, it should be illegal;
2. 80% Capital Gains Tax on property sales other than your primary residence, withheld at source.
3. Withold 40% of rent income at source, which can only be credited against taxable income in the state and country; and
4. Tax non-primary residences at 2% of their market value every year in addition to any property taxes; and
5. If landlords want out, let the state buy them out and use those properties for affordable housing for all citizens. The UK previously came "dangerously" close to eliminating landlords this way last century [1].
EDIT: another big one:
6. Ban HOAs. Entirely. They are anachronism invented to enforce segregation. Any function they perform (eg picking up trash, tending communal parks) is and should be the function of local government, which is democratic. HOAs are not.
Lastly, the one exception I would carve out is for multi-families and ADUs (accessory dwelling units). These were once commonplace but are now prohibited in most of the US.
Just like renting out a room in your house while you're there, ADUs mean the landlord is also affected by any potential misdeeds or abuse by the tenant so is invested in that not happening.
[1]: https://www.theguardian.com/lifeandstyle/2024/mar/19/end-of-...