Hold down and Keep in

Hold down verb - To set bounds or an upper limit for.

Keep in and hold down are semantically related in restrain topic. In some cases you can use "Keep in" instead a verb "Hold down", when it comes to topics like restrict.

Keep in verb - Cause to stay indoors.

Hold down and keep in are semantically related in restrain topic. Sometimes you can use "Hold down" instead a verb "Keep in", if it concerns topics such as restrict.