Special instructions for this website:
To embed a YouTube video full width, use the “Custom HTML” block rather than the YouTube embed and copy the iframe instead of the URL. Adjust the width and height to 840px and 630px respectively. Reference instructions on this website if needed: https://kinsta.com/blog/wordpress-iframe/
In contrast, the YouTube URL can be simply copied into a YouTube Block, but the video will render as 500 x 375px instead of full width.
There are a couple WordPress help pages on my website, and the Blocks documentation will help you more quickly understand the differences. I doubt you will have any trouble creating new pages, though, as most of your content are paragraphs and images.