The iPhone XS is Apple's largest phone to date (10/3/18) meaning you will need a new case if you plan on upgrading from a previous model like the iPhone X. The XS measures in at 6.20 inches (157.5 mm) x 3.05 inches (77.4 mm) x 0.30 inches (7.7 mm). It weighs 7.34 ounces (208 grams). It has also been discovered that both the iPhone XS and XS Max have slightly larger camera bumps than the previous models.
A variety of cases and screen protectors that fit the iPhone XS Max are already available on sites like amazon.com. Prices vary depending on quality and protection. Manufacturers like OtterBox offer a variety of cases for maximum protection, while Speck offers a variety of colorful options.