iPhone Dictionary

Is there a way to just "Add Word" to dictionary. Like in any other software if you come across a word that comes back as a misspelled word, you can simply right click and 'add to dictionary' or 'learn word'

The only way I can find is a convoluted manual process of adding it to a text replacement option in settings on the iphone.

Also is there a scientific english and old english dictionary option for iPhone as this is my main issue, old words and also scientific terms.

It's almost like apple wants us to not use a full remit of the english language and is pruning the linguistic capabilities of the next generations with this simple omission.