Filter Variables

Perhaps there is a way and I've just not worked it out, but... When I create a filter for "Open Tasks", I can't find a way for it to filter out tasks that are in the future. I'd love a way to set filter variables, so that instead of "date is on or before 10/17/25" for example, it can say "date is on or before [today]", or better yet, "task is not after [today]"