Same problem with me, no option there, also not working even you did anything to turn oof. SAMSUNG have simple PREDICTIVE setting for ON/OFF, My experience only SAMSUNG have simple setting mobile, only buy SAMSUNG mobile.
Go to a screen that shows the keyboard
Near the left “Space Bar” select and hold the “Dictation Key”
Then select on the “Settings” gear option
Below the section that says “Smart Typing”, select on “Predictive Text” and disable it
Another option is to disable different settings like auto-capitalization and punctuation marks