iOS has a very neat feature that turns abbreviations into full words. To create your own abbreviation shortcuts, go to Settings - General - Keyboard - Text Replacement. Tap the “plus” icon to create a new abbreviation.
Here type in the phrase you want the shortcut for, then type the abbreviation shortcut. Now to use the shortcut, just type it in any app and tap on the suggested text replacement. Alternatively, once you write your shortcut, you can hit space to automatically replace the text.
What’s your most often used phrase?