@allforhim007 What software are you currently using? Image Viewer and Shotwell do not have an option to resize photos, but there are several programs available for Linux, including RawTherapee, Darktable and GIMP that are well-known and powerful tools capable of a lot! For example, if you open the image in GIMP you click Image, Scale Image… and the tell it what dimesions you want. Don’t forget to export when you are done, so as not to overwrite your original image.
Probably the “simplest” way in Linux is to right-click in the folder where the picture is found, open a terminal and:
convert -resize 1000 DSC_1005.jpg resized.jpg
where “convert -resize” is the command, “1000” is the width of the new image in pixels, DSC_1005.jpg is the file you want to resize and resized.jpg is the new image that has been resized.