Apple is developing new iPhone designs including bigger screens with curved glass and enhanced sensors that can detect different levels of pressure, said a person familiar with the plans. Two models planned for release in the second half of next year would feature larger displays with glass that curves downward at the edges, said the person, declining to be identified because the details aren’t public. Sensors that can distinguish heavy or light touches on the screen may be incorporated into subsequent models, the person said. With screens of 4.7 inches and 5.5 inches, the two new models would be Apple’s largest iPhones, the person said, and would approach in size the 5.7-inch Galaxy Note 3 that Samsung Electronics Co. debuted in September. The South Korean maker last month released its curved-screen Galaxy Round, the latest phone in an array of sizes and price points that’s helping keep Samsung ahead of Apple in global market share.