Booking flights to australia but want to do a few days stop over in bangkok on the return flight?

Im booking flights to australia and on the return I want to stop in Bangkok. I have previously visited Bangkok but unfortunately our time there was rather limited and involved replacing my friends pport. Really want to visit again so was wondering if its possible to book flights to australia and choose to have a few days stop over because i have found flights with stop overs in hong kong/ Bangkok but only for a few hours.