This is the one thing my kids did well. First one slept through the night day one. Second took about a year to stay asleep once she was asleep.

And I’m gonna be a hypocrite here. Sleep is a learned behavior which needs to be constantly reinforced. I know parents with super easy kids who never set boundaries around sleep time which caused their kids to be difficult sleepers. Don’t ever allow them to get up after bed time and you’ll suffer a lot less. Our super difficult second kid learned we will only come into the room for short periods to meet her needs during bedtime. We started setting timers of a few minutes to let her learn that we aren’t coming in immediately when she started crying. Saved our sanity and slowly taught her to self sooth. I know it doesn’t work for all kids. But IMO a lot of parents will try to solve issues without the assumption their children can learn to tolerate mild inconvenience. It’s a huge cultural issue in the US.