PHP- boolean in if statement

I have field value $copyContent which, when dumping returns:

"true"

It's actually boolean filed which I am pulling out trough request from endpoint like:

'/api/copy/6?copy_content=true'

I want to check that if it's true or it's false. I tried:

 if ($copyContent === "TRUE") {
     echo 'Do it!'
 } else {
     echo 'Do not do it!'
 }

and also just:

 if ($copyContent)

or:

 if ($copyContent === true)

Non of this examples work as it should. Can you tell what am I doing wrong?

Update:

I tried with:

 if (filter_var($copyContent, FILTER_VALIDATE_BOOLEAN)) {}

This works.. Can this be suitable solution?