You can use Illustrator to do this.
- Open the document in Illustrator.
- Select all the elements you want to resize.
- Depending on the version of Illustrator you use:
- If you see the options bar at the top, there should be a section at the end that has the letter "W" to the left of it. That's the width (the height is right next to it). You would need to make sure the Link icon is active (so it scales proportionately) and adjust either the width or height by typing in the new width/height and adding mm (like "600 mm").
- If you don't see the options bar at the top, then choose "Window" > "Transform" to bring up the transform window. The 2nd column in this window is the width and height and you can adjust these numbers there. If you want to keep your file in proportion, make sure the link icon is clicked.