A previous dev has suggested the GTA 6 map must be lesser and much more densely packed. On the other hand, as leaks have ongoing to trickle out of Rockstar, modders have recreated the GTA 6 map in GTA 5's engine which supplies a sense of its large scale. https://reidjifyv.blogolize.com/grand-theft-auto-6-release-no-further-a-mystery-74448800