Change with-in the code, the size to large adding the l example: size="l" then save.
You will need to then go to Style properties>>Messages>>Message user info block width and change to about 200px.
Now this above seems to be ok just the way it is. I personally would leave it this way due to the fact, adding the avatar size in extra.less effects @ avatar tags and may effect a few other things around your borads. But if you really want 180x180, then after doing the above, add this to your extra.less