Display first 50 words of post content rather than description

I am wanting to add a feed with links to the original website, thumbnail image, and the first 50 or so words of content. However, the site has their feed setup so that the description doesn’t include a snippet of the content but instead “The post [link to post] [title of post] appeared first on [link to website]”. Is there a way to grab a snippet from the content section of the RSS feed instead?