Squat racks are lightweight, which makes them portable and great for home gyms. They are designed to ensure that the barbell sits in the perfect spot to ensure it won't tip over, so as long as you're using the squat rack safely and have checked the max load, you don't need to worry about stabilising your squat rack.
If the squat rack has weight storage pins, adding weights onto them can make the rack even more stable, or If you're using one of the portable two-piece racks you may consider adding some sandbags at the feet if lifting close to the max load.