I agree for fallout, but it's just to emphasize the fact that there is always a system in place to limit the player in certain area (well in most cases).Being underleveled for the world at large is very different from being physically blocked from entering the world at large.
I am strongly against level-based progression in the first place, so can't say Ive found many games to my liking. AC Odyssey did it right though. No limitations, and level scaling. You could literally go anywhere you wanted, and enemies were scaled to you. Still best option would be to focus progression on just stats, skills, money and gear and forget levels completely.
AC Odyssey (ACO), you start on little island (restrited area). After leaving this little piece of land, for me, it's not better, not worst, it's just different. An beautiful open world, lot of loots, lot of exploration, it's all good for me
Edit : I think another little detail, in my first playtrougth i spent too much time in watson before "the heist". Now, i "rush" the Act 1 directly whitout doing anything. And after that, the world is mine. No restriction apart strong enemies and StreetCred (who up pretty quick), but i can go everywhere i want, visit all vendors, ripperdocs,...