I'm looking for Star Caps headlines so unsure whether keyword case is significant, though I would expect search matching to be case insensitive?
There's no way as far as I can see to test this since the Ads Diagnosis/Preview tools don't allow this sort of testing..?
{Keyword} will capitalize only the first word (first letter of the word)
{KeyWord} will capitalize all words (first letter of each word)
If you have words where all letters should be capitalized (NATO for example), even if you write your keyword list and properly capitalize the word, the DKI will lower-case them and will show as Nato.
Every search engine is case insensitive. "abc" is the same as "Abc", "aBC" and "AbC" and all other variations.