Cool it and Mellow out

Cool it verb - Become quiet or calm, especially after a state of agitation.

Mellow out and cool it are semantically related in lessen topic. In some cases you can use "Mellow out" instead a verb "Cool it", when it comes to topics like let up.

Mellow out verb - To get rid of nervous tension or anxiety.

Cool it and mellow out are semantically related in lessen topic. Sometimes you can use "Cool it" instead a verb "Mellow out", if it concerns topics such as let up.