1. Go to files

2. “On my iphone”

3. Minecraft

4. Games

5. Com.mojang

6. Minecraftpe

7. Options

8. Export this options file to a file editor (like the “Documents” app, download it from app store)

9. Save the options file in the file editor

10. Edit the options file: gfx_viewdistance. This number is the render distance in blocks. Change it to whatever you want it to be. 20 chunks is 320 blocks

11. Export the file back to the minecraftpe folder where it came from, name the file the same as the original file, and delete the old, unedited file

In minecraft your render distance in video settings should say “10+”. If you changed the setting to 320 blocks, this means 20 chunks. Make sure you don’t set the render distance to a lower value, because you can not set it back to “10+”, you’ll have to do all of this again