if you are totally new to US,you don’t have credit history and cannot get mortgage.

Without mortgage you cannoy buy a house unless you have the money worth the price of the whole house.

What people usually do is they live in US for about 3 years,accumulate credit history by paying monthly rents and other bills on time, get the mortgage for 80% of the house price,

pay about 20% of the house price as down-payment.