How do I get the text of a particular element from an external domain webpage.

How do I get the text of a particular element from an external domain webpage?
Example: Get the text inside the element <h1 class='lawtitle'> from the webpage "https://thecorpusjuris.com/legislative/republic-acts/ra-no-11460.php"?
I actually want to create a webpage that displays a list (number and title) of Republic Acts in descending order from No. 11460 down to No. 1.

<div id='myList'>List of Republic Acts</div>
<iframe src='https://thecorpusjuris.com/legislative/republic-acts/ra-no-11460.php' width='100%' height='600px'></iframe>

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
<script>
    $(document).ready(function() {

        for (var i = 11460; i > 11450; i--) {

            $("iframe").src = "https://thecorpusjuris.com/legislative/republic-acts/ra-no-" + i + ".php";

            var lawtitle = $("h1.lawtitle").html(); // this line returns 'undefined'. Please write here the codes to get the text inside the element <h1 class='lawtitle'> from the above-mentioned external domain webpage

            $("#myList").append("<p>R.A. " + i + " - " + lawtitle + "</p>");

        }

    });
</script>