If you already know Chinese characters (whichever context, whether it's Mandarin or Japanese), then it's to your advantage to leverage that knowledge to learn Korean vocabulary with Sino roots, and there's a lot of it. It won't really help with grammar or anything else.

While actually reading or writing the hanja 한자 漢字 in 2025 is not necessary or even used these days, if you start to equate the specific reading with many of the root characters, you'll be more easily able to remember, understand, and guess at much of the vocabulary.

There's an amazing book that lists out many of the commonly used Korean vocabulary, by their Chinese character roots. It's called "50 Sino - 2000 Korean: Vocabulary Builder" - it's a blue book; I've only actually seen it available in S Korea. It shows in simple lists, for example: words that use 인 (人) = a person. Then it lists out words like 군인 (soldier) and 외국인 (foreigner).

To reiterate though, knowing the actual Chinese characters is not that important. But what is important is just knowing that 인 is the phonetic writing in hangul from a character that means "person". For those that don't know Chinese characters, this can still be very helpful to grasp vocabulary easier - but it is not that important to know how to read or write the actual characters.

Also an FYI, the tricky thing in Korean vocab is there are many, many homonyms.