The Automator app, distributed with the OS, has actions that can resize images. They might be named "Scale Images" or "Rescale". I don't recall if they preserve metadata, so you could make a test to find out.
There might even be an image watermarking Automator action, but it may vary by OS version. Type the keyword "image" into Automator's search criteria for actions, and it should list all the actions for images. Or type "watermark" (or just "water") and see what it lists.
If you prefer command-line tools, the command 'sips' can resize, convert formats, and perform various other actions on images. To read its help, type this in a Terminal window:
Or
man sips
. The command
sips -H
will list the metadata (properties) it can read, alter, or copy.
The sips option to resize to a "long side" dimension is -Z (upper-case is significant).