Keep the bits you meant to capitalize
Preview the result before copying. Preserve acronyms keeps words that already have two or more uppercase letters, such as API. For code names, word boundaries also split camelCase and acronym-to-word transitions.
A worked example
Sentence case with Preserve acronyms changes the octopus and the SEA: an API story to The octopus and the SEA: an API story. Count the converted text when it also has a word limit.
Before you use the result
Proper nouns such as iPhone need a final check. Capitalize words is mechanical capitalization, not AP or Chicago title style. Code-name modes intentionally change separators. For editorial title capitalization, choose a title style and review each word.