the AWS Open Data set includes a “photos” metadata file that you could use to search for photos included in that set as of the date of the last version of the metadata file.
that file includes height and width fields. it’s been a while since i looked, but i think those fields would reflect the original height and width of uploaded photos. it should be noted that if the size of an uploaded photo exceeds a fixed limit, iNaturalist will reduce the size of uploaded photos to 2048px along the maximum dimension (height or width). so even though it stores “original”, large, medium, small, thumb, and “square” versions of each photo, the “original” version will have a maximum dimension (height or width) of up to 2048px. large, medium, small, and thumb, will have maximum dimension of up to 1024px, 500px, 240px, and 100px, respectively. square will be resized such that its minimum dimension is 75px, and then it will be cropped to a 75px square.