Booking adjoining rooms for a family or group takes a bit more than simply booking two rooms and hoping — a few practical steps improve the odds.
Requesting connecting rooms specifically
Not every hotel room type has a connecting option even within the same property — check specifically whether "connecting rooms" (an internal door between two rooms) or just "adjacent rooms" (near each other, no internal door) is what's actually being offered before booking.
Booking directly vs through a platform
Contacting a hotel directly and explaining you need connecting rooms for a family, rather than booking two separate rooms through a comparison platform and hoping, meaningfully improves the chance of an actual connecting assignment — platforms often can't guarantee this at the point of booking.
Family room alternatives
Some properties offer a single larger family room (bunk configurations, a sofa bed, or a family suite) as an alternative to two connecting rooms — worth comparing cost and space against splitting a family across two standard rooms.
Confirming before you travel
Email or call the property directly a few days before arrival to reconfirm a connecting-room request — a booking note isn't always visible to every staff member handling check-in, and reconfirming avoids an awkward surprise at the front desk.