The 12 has the screen size of the 11 and the body size of the 11 pro. Seems like this generation, apple intentionally made the non pro better than what the 11
iPhone 11/11 Pro/11 Pro Max」は見た目がどう進化したのか前モデルも含めて徹底比較 - GIGAZINE
Apple iPhone 11 (13th Gen) Dimensions & Drawings | Dimensions.com
Apple iPhone 11 (13th Gen) Dimensions & Drawings | Dimensions.com