For 4K video editing on a phone, consider the iPhone 13 Pro or iPhone 13 Pro Max. They feature powerful A15 Bionic chips, advanced camera systems, and optimized software for seamless editing. Another option is the Samsung Galaxy S21 Ultra, which offers a powerful Exynos or Snapdragon processor, a high-quality camera setup, and a vibrant display. The Google Pixel 6 Pro is also worth considering, with its powerful Snapdragon processor, advanced camera capabilities, and stock Android experience. These phones provide the necessary performance and features to handle 4K
video editing tasks efficiently on a mobile device.