Why phone photos are big
Phone cameras save pictures at 12 megapixels or more, so one photo is often 2 to 8MB. Forms and chat apps usually want far less.
Step 1: open the compress tool
In your phone browser open the compress image tool, or go straight to a size such as 100KB or 200KB.
Step 2: choose the photo
Tap "Choose an image" and pick the picture from your gallery. It stays on your phone and is not uploaded.
Step 3: download
Check the preview and tap download. The new file is saved to your Downloads or Files app.
If it is still too big
Crop away empty space first, or pick a slightly higher target. You can also reduce the pixels with the resize tool.