No, because knowing the first child is a boy doesn't tell you any information about the second child.

Three doors, Girl Girl Boy

You select a door and Monty opens a door to show a Girl. You had higher odds of picking a girl door to start (2/3). So switching gives you better odds at changing to the door with the Boy because you probably picked a Girl door.

Here the child being a boy doesn't matter and the other child can be either.

It's 50/50 assuming genders are 50/50.