A 1:1 macro lens such as the EF 100mm f/2.8 IS Macro will get you very close, but might not get you quite all of the way to where you want to be. There's a unique lens that will give you much more room to play with: The Canon MP-E 65mm 1-5x Macro Lens.
This lens is designed to do one thing only and to do it very well: shoot macros. In order to excel at macros, it gives up most of the versatility of more conventional macro lenses. It can shoot only macros and nothing else.
At each magnification setting it only has a single focus distance. At 1X the working distance (the distance between the front of the lens and the subject) is a bit over 100mm. At 5X the working distance is a mere 41mm. The working distances are printed on the lens barrel right next to the magnification markings. The easiest way to focus without changing magnification is to use a focusing rail on a tripod. A focusing rail allows you to slide the camera forward/backwards to move the point of focus with respect to the subject.
Although Canon calls it a 65mm lens it doesn't really have a focal length in the conventional sense at all. Focal length is defined using collimated light at infinity. But the MP-E 65mm 1-5X Macro can't focus at infinity at the register distance for which it is designed. As mentioned above, it can't focus at any distance except the minimum focus distance at each magnification setting. To focus the subject without changing the magnification the entire camera must be moved forward or backward until the desired point on the subject is in focus.
What you do get when set to 1X is a field of view at 1:1 that is equivalent to a 65mm lens focused at a 1:1 reproduction ratio. What you get at 5X is a field of view at a 5:1 reproduction ratio (yes, 5:1 and not 1:5) that would be equivalent to a 325mm lens focused at a 5:1 reproduction ratio if it were possible for a 300mm to extend that far and focus on an object located somewhere between the front of the lens and the sensor!
Another option to increase magnification is to use extension tubes or a teleconverter with a Macro lens or even a non-Macro lens. Just be aware that using extension tubes with a macro lens is a tightrope of sorts: The longer the lens' focal length, the further you need to extend it to get the same increased magnification. With standard extension tube lengths you increase the magnification of longer focal length lenses less than you increase the magnification of shorter focal length lenses. So extension tubes work better for most users with shorter focal length lenses. With a 25mm extension tube the EF-S 60mm f/2.8 Macro has a MM of 1.61X. The EF 100mm f/2.8 IS with a 25mm extension tube increases to 1.39X.