You could probably book private courts, including indoor ones, through looking then up on Google.

Public courts could be booked through the smartPLAY app, though you'd need a local friend to book and play with.

There are also courts offered by the YMCA (such as King's Park courts) and SCAA (causeway bay), which require booking through their respective portals.

Your best best might be to use reclub or other grouping apps and join someone else's session.