Yep, that works too. I wrote the shortcode because I didn't want to have to manually resize pictures. That's effort and it means if I change my layout to require wider pictures I have to go find the originals.

I think you could do this with a render hook if you want to get fancy (with the benefit that the Markdown for your posts stays as plain Markdown): https://werat.dev/blog/automatic-image-size-attributes-in-hu...