when you search 'order:score' in other channels like sankaku or imouto, the pictures that has the highest scores come up first. Does gelbooru have something like that too or no?

Not yet.

It's not quite documented yet, but you are able to do searching such as: loli sort:id:asc

You can sort by: id, rating, score, user, height, width, parent, source, updated

We are not sure why someone would want to sort by owner, but figured to allow it since it will be requested for some random reason.

Are we talking, tag section or post section?
Perhaps it is Tag section, which doesn't help me much.
AS stated elsewhere in the tracker, shall I create another Feature request? Cause it seems the last one I made was overlooked by a great Margin.

Post section.