@Dave S And the OPTION is called ["." Shortcut] it is the only OPTION that refers to a PERIOD, and turning it off has no effect
its at the bottom of the "GENERAL -> KEYBOARD" screen, but again.. no effect
That's exactly the right setting. And turning it off does make my iPhone insert two spaces instead of adding a period. I've seen some people try to "slide" a switch in iOS to toggle between on and off. Just tap it. If you try to slide before lifting, it is too easy to be like a mouse click where you move off the button before the mouse up.
Personally I prefer to leave the option on. I've always liked the feature myself, especially since the default character keyboard view does not have room for a period (unless using an iPad). Ironically, I've always found it an intuitive method precisely because:
@Dave S And yeah, I'm creating something that requires "old school" typing...
And as one who personally learned touch typing using old manual typewriters over 45 years ago, the standard at the time was to always put two spaces between sentences. (Some will argue that is more readable when using fixed pitch fonts, which of course manual typewriters were at the time. See also this recent study.) So when typing I've always used two spaces making this option very natural to me. I just don't type the period (since not available on the default view anyway) but I still get the period.
And it doesn't very often otherwise interfere, despite the Chicago Manual of Style not liking it.