Adding additional multifamily to existing duplex

[Paulo Patam]

Hello, so I am super new to investing and I am still on the search for my first multifamily. I live in Nevada and I found a property in Las Vegas that currently has a duplex on it. The listing agent has marketed the property as an investment property with more land that is capable of building additional 4plex up to 8 units on the property. So my question is more on the finance side of investing. Is there a loan that bundles a full build with a loan? Because I know that you can 203k loan for renovations/rehab but would a new build still qualify under this? If not is there such a loan? And also would it be wise to just get the loan for just the duplex now and wait few years for some type of appreciated to refi and then use the money to build or just tried to build to 4/8plex right away? Is this a better route to take? Please pros lend me your knowledge and experience. Anything is greatly appreciated. Thanks in advance.