Collapsible Content

@tamino-haas here they are

Show and hide:

$w.onReady(function () {

    $w('#buttonID').onClick(() => {
        if ($w('#elementID').hidden) {
            $w('#elementID').show();
            $w('#buttonID').label = "Read More"
        } else {
            $w('#elementID').hide();
            $w('#buttonID').label = "Read Less"
        }
    })
})

Expand and collapse:

$w.onReady(function () {

    $w('#buttonID').onClick(() => {
        if ($w('#elementID').collapsed) {
            $w('#elementID').expand();
            $w('#buttonID').label = "Read More"
        } else {
            $w('#elementID').collapse();
            $w('#buttonID').label = "Read Less"
        }
    })
})

EDIT: You are likely going to want to label the button within the editor as Read More to begin with