If you continue to study in China for two years until you graduate from university, you can apply for a postgraduate degree.
In China, you can only learn Korean roughly, so it's good to learn pronunciation correctly. Don't be too hasty. If you have passed TOPIK Band 4 in China, your level is just doing problems, and your oral English and listening skills are not good at all, let alone listening to the lectures given by professors in graduate schools. So don't worry too much about learning Korean in China, just pass TOPIK level 2. After going to Korea, I entered the Language Institute from the third grade and studied for another six months. Use this half a year. Go to a big church in Korea and meet some Koreans. They are very enthusiastic. Ask them to tell you which school is good and which major is good. I'm sure their introduction is better than that of the intermediary 100 times. Then take a TOPIK4 exam and prepare for graduate school, that's all. Band 4 is not difficult at all, as long as you work hard, you can pass it.
If you go to Korea for postgraduate study, your language will improve rapidly. It won't be too difficult to take the TOPIK advanced exam then. If you want to find a job in Korea, you must take the TOPIK advanced exam and know some English. . .
Go back to China to look for a job. Unless you have connections and someone can find a good one, you might as well not go abroad.