Isolating images in uploads not used/recognised by Wordpress

I am looking at a website which has a lot of images in the uploads folder – but these images do not appear to be used by WordPress and do not exist in the media files.

It does appear that the original site is fairly old (2016). The images are scattered across multiple months/years. It also looks like there are multiple versions of these unknown images with different sizes.

Is there any easy way to programmatically find and remove all files in the uploads Directory which are unknown to WordPress? (If it makes any difference the OS is Linux and I am competent at the command prompt).