Enlarge some logos from supplied images

I have a collection of approximately a dozen logos of beach bars and places of interest that I visited whilst sailing in the Caribbean and I want to create a table-top image in my VW camper van incorporating these images in a random/haphazard manner.

Unfortunately, some of the images are little more than thumbnails at the moment and I'd like to have the images 'enlarged' and then 'jpegged' as larger images that can be used by my table manufacturer.

In the 'old days' this could be achieved by using a pantograph but there must be a modern day, electronic, equivalent (scanning?) that could be employed?!!

If you know how to achieve this, I'm looking for output images circa 6 megapixels which I can forward to my table manufacturer.

Brgds