SIZE does matter, but it is not a linear relationship of bodyweight vs weight lifted. The correlation depends on the lift, and there are other factors like the lifter's anthropometry. Although it's tempting to think about how much you can bench or deadlift in terms of bodyweight, this sort of approach will usually flatter the lighter lifter.
You can attempt to figure out some bodyweight vs weight lifted coefficients using statistics - there is plenty of lifting data out there to play with.
There have been a number of attempts to figure out coefficients to normalise lifters' results across different weight classes in both olympic weightlifting and powerlifting, eg Hoffman formula, Wilks coefficient, Glossbrenner formula, etc. There have been many arguments over the years of the pros and cons of each of these approaches, but you can get a general idea.