For the two common types of rats in Canada, the tail to body length ratio can be used to help identification. The black rat has a tail that is longer than the body, so it’s not that. The brown (Norway) rat has a tail slightly shorter than the body, but the body can be 6-11” long. When viewed from above, a mouse has a triangular shaped snout, whereas a rat has a more blunt one. Based on those things, it’s more likely to be a mouse, but it does seem quite large for a mouse if your recollection is correct.
Where I live, cutting the grass disturbs voles, which look like very large mice.