You can turn on a daily email that will tell you who is out of the office today and tomorrow and also a Slack integration which will send these notifications to a Slack channel of your choice.
Navigate to your company settings.
Click on the Reminders tab.
You can then choose to send daily "who's out?" email and the time this should be sent and who should receive it, decide whether to send this even if there is nobody out and integrate your account with Slack to receive the notifications in a Slack channel.
Please also be aware that your timezone settings will affect the time this is received. If an individual profile time zone is set differently to the office timezone, staff will receive the notification according to their profile settings.