Thanks, judysings
I had found this Pages - Preferences - Autocorrect place all on my own. 'Automatically detect lists' and 'Symbol and Text Substitution' are not checked, and the substitution list only contains the typical copyright/trademark stuff, anyway. Also, when I go to System Preferences - Keyboard - Text, the spelling 'Replace/With' list is empty.
So it is still a mystery to me why I typed in 'party'' the other day and suddenly the word was replaced with a festive emoji. Crazy; I don't understand. When did I opt in to this emoji stuff? I'm old; I don't do emojis except on WhatsApp, and even then it feels a little weird. As usual, it is probably 'user error'. I am likely hitting some key (fn/control?) by accident and only on occasion.
I should probably also mention that I am using an Israeli Macbook Pro, so the keyboard is setup a little differently and has some pretty strange stuff on it. For example, when touch-typing I am routinely missing the caps key on the left or accidentally vowelling my Hebrew from time to time. Not an easy keyboard or set up to work with. When I am back stateside I will probably upgrade to a non-Intel chip box with a plain-vanilla, American keyboard. Maybe that will finally solve my problem.
Thank you for your prompt response. If only my kids answered me so quickly!