By default, the WordPress user profile description is limited to plain text. A rich text editor can make user profiles more visually appealing and easier to read.
Here’s the complete code that you can add to your functions.php file:

<?php
function custom_user_profile_description_rich_text($user) {
    wp_enqueue_editor(); //Enqueue the WordPress editor assets.

    ?>
    <script>
        
    document.addEventListener("DOMContentLoaded", function(event) {
        
        var id = 'description'; //Field ID for the user description textarea
        
        // Initialize the TinyMCE editor
        wp.editor.initialize(id, {
            tinymce: {
                wpautop: false,
                forced_root_block : false,
                convert_newlines_to_brs: true,
                toolbar1: 'undo redo | bold italic underline strikethrough | alignleft aligncenter alignright alignjustify | outdent indent | bullist numlist | forecolor backcolor | link unlink image | code fullscreen',
                toolbar2: 'formatselect fontselect fontsizeselect | table | hr | alignleft aligncenter alignright | subscript superscript',
                fontsize_formats: '8pt 10pt 12pt 14pt 18pt 24pt 36pt',
                menubar: true,
                image_advtab: true
            },
            quicktags: true,
        });
    });
    </script>
    <?php
}

//Add this to show the editor on the user's profile page
add_action('show_user_profile', 'custom_user_profile_description_rich_text');
add_action('edit_user_profile', 'custom_user_profile_description_rich_text');

// Allow HTML in user description.
remove_filter('pre_user_description', 'wp_filter_kses'); // Remove Deafult filtering that strips HTML
add_filter('pre_user_description', 'wp_kses_post'); //Allow certain HTML tags in the description 

Adding a rich text editor to the WordPress user profile description field can significantly improve the user experience. By adding this code you can easily integrate TinyMCE into your WordPress site and allow users to create rich, formatted content in their profiles.