It will help in Lightroom (or other converter) to reduce the size to 2024 x 2024 or as close to a square with the widest 2024 px. Larger images are automatically reduced to the widest 2024. And in most cases there are no issues. In extreme landscape (or portrait) format the reduction will be too much to fit the 2024 and the image quality is noticeably poor. I have seen some that was impossible to ID. In addition when looking at the thumbnail, in the gallery, the subject has completely disappeared from view. Reducing the image size to 2024 x 2024 provide the best possible control over the quality of the picture and it is presumably faster uploaded.
Yes, what @kildor and @robertarcher397 said. Also, instead of reducing the dimensions of the whole image, it’s often more helpful to crop the image to the species you’re identifying (or wanting identified).