Can you add blank space to a photo in Mac Preview?

I would like to add a title above or below a photo that is open in Preview. I know how to annotate the photo that writes over the photo. I want to add a new blank area where I can put the annotation.

A simplified method that works just as well:

1. Open your picture in Preview.
2. ⌘ command + A and then ⌘ command + C to copy it to the clipboard.
3. Go to Tools > Adjust Size... and enlarge the image to the overall size you want for the canvas. (I would make it bigger than you need as it is easy to crop at the end.)
4. ⌘ command + A and then delete to remove the enlarged image
5. ⌘ command + V to paste back the original, smaller image onto the enlarged canvas.
6. Choose Convert when asked to "Convert this document to PNG" (as you can always convert back to JPG later).

Here's the hack I did, maybe it will help other people:

1. Get the size in pixels of what you want the canvas to be
2. Generate an image of that size here: https://placehold.it/{W}x{H} (e.g. https://placehold.it/350x1136)
3. Copy the image (Control click, copy image)
4. Open Preview, press ⌘ command + N or File > New From Clipboard
5. In the new image, select all ( ⌘ command + A) then hit delete
6. Copy your original image(s) into your new canvas, reposition as needed

It's a hack, but it works. If you need anything more precise, then you'll probably need a proper photo editor.

The above methods didn't work for me - once saved the image would revert back to the old dimensions. Adding an extra step made it work.

1. Open in preview
2. Copy the image
3. Resize the image to desired size using Tools > Adjust Size
4. Paste back in the original image (and position it as necessary)
5. Add two lines in preview that span the entire image
6. Set the colour of the lines to fully transparent

The final image has the desired dimensions with blank space around it.