Can I call an anonymous function inside a tag linked to an external js file?

HTML File(firstHTML.html)

<!DOCTYPE html>
<html>
<body>

<h2>My First Web Page</h2>
<p id="demo">First Paragraph</p>
<p id="demo2">Second Paragraph should be something different</p>
<script src="myScript.js">
    show3();
</script>
</body>
</html>

JavaScript File(myScript.js)

let show3 = function() {
document.getElementById(‘demo2′).innerHTML=’I am trying to change the second paragraph using an anonymous function in an external JS file’;

};

I was expecting for the show() function to run since it’s below the

tag. I am still learning about javascript scope so it’s entirely possible that anonymous functions don’t have a global scale and so my function won’t run but why is my question. Thank you all in advance.