I own a 3000 sq ft house with exterior walls made of concrete block and stucco. The interior walls are "standard" wood frame covered in drywall. I have an attached 4 car garage (about 1000 sq ft) also made from block and stucco framed out and covered in drywall. I have an Orbi Base (RBR50) and one satellite (RBS50). The base sits in my office in the far northeast corner of my single story house. The satellite is about 60 feet away with 3 interior walls between them. I get very good coverage throughout my house and garage. I also get decent WiFi signals within 50-60 feet outside the house. I live in a semi-rural area with my neaest neighbor over 100 yards away so I don'thave any competing signals disrupting my Orbi WiFi.
This coverage pattern did not happen immediately after I plugged in the Orbi! I had to adjust the location of the base and satellite several times to find a good compromise. Additionally, I did a "sweep" of signals outside my house to find a clear channel for both 2.4 gHz and 5 gHz bands. All these steps have given me a stable, strong signal as I mentioned above.
In your case, I'd start with an Orbi base and one satellite. Adjust the things I mentioned to get the best coverage and add a satellite if necessary later. As the car manufacturers say: "Your mileage may vary." Good luck!
