Use an online photo editor with a Red-Eye tool (upload photo, select Red-Eye, click/drag over the affected area, save/export).
Use Adobe Photoshop (open photo, Zoom in, select the Red Eye tool, click the pupil, adjust if needed, save/export).
Use GIMP (open photo, use the Red-eye Reduction tool, adjust settings, apply, export).
Use Microsoft Photos (open photo, Edit, choose Red-eye/Retouch (if available), apply effect, save).
Use Apple Photos on iPhone/iPad/Mac (Edit, use the Red-eye correction/retouch option if available, save).
Use Google Photos (open photo, Edit, look for Retouch/Tools, apply Red-eye correction if available, save).
Use a mobile retouch app with Red-eye or Healing tools (open photo, use Red-eye/Retouch, apply, export).
If Red-eye tool isn’t available, use Healing/Clone/Spot Healing to replace the red area with nearby skin/eye color (zoom in, carefully sample adjacent pixels, save).
For best results, work at high zoom and apply small corrections per attempt, then export in the desired format/quality.