Sorry for taking so long to contribute to this thread but I have only just come across it.
There are a few ways of projecting or making images of various sizes for tracing of photographs taken on digital cameras.
Some digital cameras can be connected direct to a suitable projector. You can then trace direct onto your chosen support.
Or you can download your camera images to a computer then use a printer to print onto tracing paper. Works better if you print in black and white if you can.
The problem is most home printers only print up to A4 pages which will only give you a maximum of approximately 28cm x 20cm print size, though if you have a photo editing program you can select different parts of the image to print and tape them together then trace onto your support. The other advantage of photo editing is the ability to alter the brightness and contrast.
I believe there are programmes that can turn the image into a drawing, though I have never used or seen the results.
If you have a scanner you can of course scan photo or prints.
Most public libraries have scanners that can produce up to A3 as do most photographic shops and have diy machines that can make prints from your camera or your card if your camera uses one I’m not sure what the maximum size available.
If you intend to scan anything be aware of copy write law!
Regards to all