Howdy! Sorry for my late reply.
Attachment pages shouldn’t be indexed for most sites because they offer little SEO-worthy content. They’re there because WordPress uploads files to “post” objects, which show only the uploaded files. This is why we added “noindex” to them by default.
With WordPress 6.4 6.4.3, on new installations, these media posts automatically redirect to the page where the attachment is uploaded, or to the real attachment when a page isn’t available.
For the millions of older installations, we also have a free extension available that does this, called Origin. It does precisely what you’re asking about.
This extension isn’t necessary for SEO unless you (accidentally) link to an attachment page — much older versions of WordPress used to do that automatically for every file you embed on a page.
