The existing answers (about informing your manager, making your team aware in Slack, blocking off time on your calendar, etc.) are good, but I think the one thing missing is asking your Manager and/or team how to request and communicate time off for appointments.
Everyone has appointments and sometimes they are during work hours. There is nothing wrong or unusual about it. The variable is how teams request and communicate it.
So before you try the suggestions, I recommend asking how the team handles these things and then follow the team's method.