Smaller photos can sometimes hold more detail than larger ones, they are by no means inferior and you should consider them for enlargements.
Have you ever seen those small photos around 3×2 inches? Tiny prints that are probably found in an old album. They would have most likely been printed on an old printing machine like this.
To make a print you would insert the paper under a red safe light and insert the negative in contact with the paper (hence the term contact printer!). Close the lid and press the button for the exposure and develop the print with trays and chemicals. The resulting print would be the exact same size as your negative. The reason was photographic materials were expensive. Small prints were economical and a small contact printer was too! They were most likely devolved in the under stairs cupboard.
The beauty of this process was that the print has as much detail as the negative. Decades on when the negatives are lost and all that is left is the print, we need not worry, that print is most likely still razor sharp and contains loads of detail. Just look at this version below. So sharp even when a massive blow up is made.
I have taken a small portion from the larger scan to show just how detailed they can be. You can see how bad this chaps teeth were, which is a testament to the quality and methods of making prints direct from negatives in the 1930s.
The point i am trying to make is, smaller is sometimes better when it comes to prints.
It is is possible to make huge blowups from these images and in some cases as big as 30×20 inches and still look great! Have a search through your grandparents photo albums and see what you can find. If you find some 3×2’s scan them in and blow them up or send them in here. You’ll be amazed at the hidden details not visible at such small sizes. Extra figures appearing at windows, cats or dogs hiding in the shadows, odd socks, string holding up the trousers or holes in clothes. Perhaps even missing teeth or bruised or dirty faces. Unless you do it you will not find out. Take my word for it, it feels like being a detective!
So don’t despair if you only have tiny old prints in the album, even the small ones can hold masses of detail I can use to restore and enlarge for you!