How to increase rent 300% in 90 days?

[Frank Closer]

I know the subject title is bananas but hear me out. I'm looking to purchase a single family rental from my great aunt, it's located in a piping hot Downtown Charlotte NC neighborhood. Do to her age and desiring to be hands off, she has kept the same family in the property for nearly a decade at 1/4th the market rate. Well I'm not a sweet old lady, I have lots of rehab experience to bring the property up to sexy. This will be my first rental property, what are the tenants rights, as far as the property changing ownership and the new landlord wanting to attract higher end tenants. How does the process work? I'm new to REI, but I imagine I can't leave from the closing office, go to the property, and hand the current tenant a letter that their rent will be increasing 300% in oh let me see, 90 days.