A scanner needs to have been designed to cater for film scanning, as it needs to put the light source behind the film/slide. I don’t know about your model of Canon. One of the best ways to scan film/slides on a “reasonable” budget is to use DSLR/mirrorless camera with a macro lens, and a light source behind the film. There’s a little device called the Pixl-latr designed to hold the film flat on the light - which can simply be a phone or tablet screen showing a white image! Another route is to use a slide copier - I have a 35mm one of these. Again in conjunction with a digital camera and suitable lens (instead of a film camera as it was designed for).
There’s quite a few film enthusiasts around still, who will usually have the equipment to scan one way or another. Maybe you could find out if you have a local club or something… just thinking aloud!
Either way, if you find someone to do them, make sure that they can provide you with a RAW file (if they use a camera) or other wise I think a TIFF file in as high quality as possible would give the most options for restoring.