With the Boost theme, you can use the Alto editor and customised HTML code in a label to get a button which when clicked will expand content under the button. Example code looks like this. You can click the button in the normal editing mode to edit the text and then collapse before saving. This site has lots of info around Bootstrap classes and editing - https://moodlesports.univ-brest.fr/Documentation/assets/bs_components.html much is applicable to MoodleCloud I think.
<!-- button types are btn-info btn-default btn-primary btn-success btn-warning btn-danger -->
<p><button class="btn btn-info collapsed" data-target="#demo" data-toggle="collapse" type="button" aria-expanded="false"><i class="fa fa-plus-square"> Click here to read more</i></button></p>
<div style="" id="demo" class="collapse">
This is the text or content to be displayed under the label.
It looks like this: