Seeking advice on cash-out refinance to invest in deals

[Marty D. George]

Hi everyone, I'm a rookie and would appreciate some feedback on an idea I had to extract some more value out of an investment property. 

I fully own a property and make good rentals on it. I am considering a 30-year fixed loan of around $240K (APR 7.268%, $1,646 monthly payment) from Rocket to invest in real estate deals. I've been having an eye-opening discussion with ChatGPT to understand how the rate of return I need to service the debt (roughly break even) went from the 7.268% APR to around 8.23% (after tax) to around 11.83% (pre-tax, assuming a 27.8% effective tax rate based on my income, federal tax bracket, and state). 

I want to achieve greater cash flow by leveraging more of the value in my rental property. So, how realistic is it that I can effectively borrow at 11.83% (the effective pre-tax return I'd need to make the monthly mortgage payment) and make returns of at least 6% (requiring an investment return of almost 18%)? 

I need more regular, monthly cash flow (that's what prompted my interest in leveraging the value of my owned property). Do real estate deals typically include regular monthly payments I'd need to service the debt or only lump-sum payments when a property is sold?

What am I missing? Thank you!