Extracting just an image from a post

I’m probably just not understanding something with the template language, but I was curious if anyone has a link or ideal example to see someones code for extracting an image from a post to be used in a twitter card/og:image.

I’m trying to build a single photo a day blog template, and the homepage/index.html template keeps throwing me for a loop, since I’m returning rage first 1, and then in the single template it’s just a single post, but I want to extract the posts image from each of those.

My post uses a shortcode to pull generate image sizes for srcset and caption data. One image per page, with a post date and credit/sourceURL in the front matter.

My apologies if this is a stupid question. I’m just not seeing anything quite like that in docs. Which makes me wonder if I went about my template the wrong way.