On the Mac, you can type any character available in there Unicode standard, just by opening up the Emoji & Symbols viewer (Control-Command-Space) and picking the one you want. The selection on iOS is much more limited. Even finding an ellipsis is such an odyssey I can never remember whether it’s available or not. But UniChar changes that. It’s a Universal iOS app that brings every single Unicode character to your device.
This app can type every Unicode character ever on your iPhone

Photo: Jordan Hipwell