How do I import an EPS file into Illustrator?
Choose "File" > "Place" from the top menu bar and find your EPS file in the directory. If you select "Link", Illustrator will create a link to the EPS file, and if you deselect it, the file will be embedded in the project. When you're happy with the settings, click "Place".
Using Adobe Illustrator to resize the graphic:
Select the whole barcode.
Right Click > Transform > Scale Options >
Scale Stroke & Effects (tick the box).