You can use a scheduled meeting or your personal meeting room to host virtual office hours. If you plan to be online and available for a set amount of time on a given day, consider using the waiting room feature of Zoom meetings; this will allow you to speak with one student at a time, and you can let students in to the meeting as needed. This help article from Zoom Support steps through the necessary settings and implications of using a waiting room in meetings.
Note: using a waiting room for live class sessions may be confusing for students, so either use your personal meeting room only for office hours, or schedule a meeting for office hours that is different from your class session link so that you can control the settings for each meeting.