There are lots of calendar apps that you can use to schedule office hours. I found Calendly to be easier to set up than most of the others. They all are priced around $1oo per year for features like Zoom integration which will save me more than $100 of trouble.
The following video shows how easy it is for students to schedule, for me to see the scheduled appointment, and to have a Zoom link created. The learning curve to figure out how to set up 20 minute appointments, block the calendar times, and integrate Zoom was good. I could not instantaneously figure it out. I did not have to resort to Google to search how to do anything, however and had this set up in about 20 minutes.