Open the Photos app
Select the video you want to edit
Tap Edit
Trim the video by dragging the start and end sliders
Tap the crop icon to rotate, straighten, or crop the frame
Tap the filters icon to apply a filter
Tap the adjustment icon to change brightness, contrast, exposure, and more
Tap Done to save your changes
Choose Save Video or Save Video as New Clip if prompted
Use iMovie for more advanced editing
Open iMovie and tap Create Project
Select Movie
Add your video clips
Trim, split, and reorder clips as needed
Add text, music, transitions, and effects
Tap Done and export the final video