Galaxy S9 and S9+ are a bit thicker and wider, and slightly smaller than the S8 and S8+
Samsung Rugged Carrying Case for 11" Samsung Galaxy Tab S9 Tablet, Stylus - Black - Bump Resistant, Drop Resistant - 10.4" Height x 6.9" Width x 0.8" Depth - Walmart.com
Samsung Galaxy S9 Plus review: The Galaxy S9 Plus is terrific, but wait a month until after the Galaxy S10 arrives - CNET
Samsung Galaxy S9 Dimensions - Phones Size Chart in inches and mm
Samsung Galaxy S9 Size | Phonetradr
Samsung Resets The Premium Smartphone Bar With Galaxy S9 And S9+ At Barcelona Unpacked Event