If you just want to attend the meeting and listen to what scholars say, there is generally no requirement. As long as you are interested and have a seat, you can go. If you want to submit a paper and are invited to be a guest speaker, you need to submit the paper to the meeting for review, and you can participate only after it is approved. Of course, different conferences may have different standards for papers. According to the published conference information, some academic conference information platforms will publish conference announcements on a regular basis, such as A Scholar, Conference 123. You can pay attention to it.