A previous dev has suggested that the GTA 6 map really should be smaller and even more densely packed. Even so, as leaks have ongoing to trickle outside of Rockstar, modders have recreated the GTA 6 map in GTA 5's engine which offers a sense of its large scale. https://grand-theft-auto-6-traile07494.shotblogs.com/the-2-minute-rule-for-grand-theft-auto-6-release-50223106