How To Use Property Value As Down Payment For Another Property?

[Ty Shoats]

If I was to purchase a commercial property lets say for $600,000 and put 20% down payment of $120,000. (Property A)

When I buy another property for $600,000, (Property B)

How would I use the first property as down payment for the second property?

1) Can I use (Property A) full value $600,000 as down payment/collateral for (Property B)?

2) Or do I use the equity in (Property A) of $120,000 as a down payment/collateral for (Property B)?

3) Or can I do both?

Can someone please explain to me how this works in detail? Thanks so much