If your house doesn't have a dog door, your dog can learn to ask to go outside when they need to use the bathroom. Try hanging a bell by your door and teach them to ring it to go outside. Hang the bell in a place that is easy for your puppy to reach and start by ringing it every time you take them outside. Every time they touch it and it rings (accidentally or not), bring them outside for a bit. While house training them, ring the bell every time you take them outside to go to the bathroom. This will get them to associate outside with going to the bathroom and ringing the bell. If they seem nervous to touch the bell on their own, try putting a treat like peanut butter on it and take them outside whenever it rings. Pretty soon they will graduate to ringing the bell when they need to be let out.