Advanced body metrics like arm length and hand size are a big part of the scouting process in the NFL but I haven't heard anyone employed in the NRL ever bring it up in their conversations with me.
With that said there are absolutely athletic profiles that teams are scouting for on a positional basis. Melbourne really pioneered the way on the craze for tall, athletic props in recent times. While other teams have fielded singular props in that vein, the Storm not only have a first-grade pack full of them but their lower grades and even cast-offs (Dean Britt etc) are loaded up with that type. It really is their pack identity.
My gut feel is that I think we are probably a little less single-minded in our internal scouting profiles for props. We absolutely have a number of young kids that will draw comparisons to props from Melbourne and probably more so in recent times but if you really want to distill the scouting process down...you always want the biggest, fastest, strongest, smartest etc player in every position. At some point though you have to compromise because you don't have unlimited resources internally and the talent pool isn't infinite. Even then, there are guys like Nathan Brown who sort of break the rules and kick arse despite their considerably smaller stature.
Back to your original question though, I would not be shocked if Melbourne prioritised wing span (and maybe hand size). It gives greater leverage and reach when fending and offloading while bigger hands probably translate to marginally superior ball security. In defence it gives each defender a larger 'soft zone' of coverage to use their arms to otherwise make up ground for a tackle on top of greater ability to wrap up the ball. Perhaps they might even apply it for wingers given that they can do so much with so little space these days and every extra centimetre of wingspan is potentially an extra try or three scored in the corner or bomb defused over the course of a season.