There are always two situations after the interview:
First, after the interview, HR will ask you when you can start working. The answer to this question is also technical. If you answer that I need to go back and think about it for a few days or days, then HR doesn't like your answer that there is no perfect special reason.
His favorite answer is that you can join at any time, because you have negotiated before and are satisfied with you in all aspects. If you postpone the entry time, then he will also consider whether you have other interviews, so that the company will become your alternative.
Second, if he says you have to wait for the notice, there are two situations. First, he is satisfied with your interview, but he doesn't want to show it directly, so he keeps a sense of mystery and makes you doubt the attitude of the company, so he says to you, go back and wait for the notice. If you are confident in your interview, then the person waiting for the notice is usually the interview.
There is also a situation that there are many people interviewing for this position and the competitiveness is relatively strong. You are just one of them, and HR has a more suitable candidate. I just don't refuse you first and leave you hanging. If during this period, the person HR likes chooses another company or changes, then you are more likely to receive the notice.