Land tax is state based tax and every state has their own rules.  I’m located in NSW, so my comments will be based on the NSW rules.

If you buy a property with your spouse (or any other person or entity), one of the ownership structures in NSW is called Joint Tenants.  This ownership structure treats you as one owner, regardless of how many joint tenants there are, for land tax.  You will only get one land tax threshold exemption.

A workaround for this is to purchase the property as Tenants in Common.  This ownership structure gives you a legal entitlement to a certain percentage of the property.  For NSW land tax, the property now has multiple owners and therefore every owner gets their own land tax threshold exemption.

If you buy a property in NSW with a discretionary trust, you do not get a land tax exemption threshold.  Currently (2024 $1,075,000).

Note: Land Tax is on the land value, not on the property value.  Units and townhouses, etc, do not have a lot of land.