Hello Taiwan Coleman,
I believe you mean 0.5 and 0.7, because lead is measured universally by milliliters and the biggest lead I’ve seen professionally used is 2.0mm which I actually use professionally. Steadtler make great lead holders btw. Mechanical pencils are simply that, they’re lead holders. Animation Paper has a great system for traditional pencils, so you can set the size which is already set by millimeters and on your art tablet/display you should be able to turn tilt off. Turning tilt off will allow the pencil stroke to stay at a 45° point. This will allow the mechanical pencil effect you want. I hope this has helped you. Have fun animating.