All these documents don't contain the word "coke" but they do contain "Smoked", I think the app search also matching word those have the same sound. is there any way to disable this?
That behaviour is as expected. App Search leans towards recall over precision, so it casts a wider net. There isn't a way to disable that behaviour, though you can use some Lucene Query Syntax functions to refine your search,.
In your example, it will also look for terms that are similar to "coke" - so in this case, the "oke" in smoked is the closest match in your document set. Of course, if you did have any documents with the term "coke", those would surface first (if not, try adjusting your relevance tuning settings).
If you use any Boolean syntax the matching logic becomes whole-word rather than partial word so you can use any of these to match just coke and not smoke:
"coke"
coke OR coke
coke AND coke
coke NOT thisWordDoesNotExist
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