Is it possible to buy many properties through traditional lending

[Michael Hartman]

So from excerpts from books I have listened to about real estate investing, one question is at the top of my mind.  I am not at the point in my journey to buy a home just yet.  For my first investment property purchase if I went through a lender and my debt income ratio allowed me to purchase something for 250k and then I rented it out.  Then 1 year later I refinanced or found outside funding and had the finances to purchase another property... could I?  My earned income from my w2 job would pretty much be the same from the year before and the cash flow from the rental would be a few thousand for the year.  If getting loans is based on debt income ratios then I think this way would not allow me to continue building my portfolio.  If I am wrong please educate me on what I do not know.  If I am correct then how can I continue buying properties in a situation where I am not loaded with liquid cash.  Please and thank you for everyone who responds.