CalcSD has a list of all available medically-measured studies:
https://calcsd.info/study4.html
Here's all the BPEL and BPSFL studies grouped according to their location:
* Asia
Hwnag: 4.61" (0.71)
Choi: 4.61" (0.75)
Son: 4.69" (0.51)
Chen: 5.08" (0.51)
Wu: 5.25" (0.44)
Yoon: 5.28" (0.54)
Wu & Yang: 5.32" (0.43)
Park: 5.33" (0.66)
Wu: 5.47" (0.44)
Park: 5.54" (0.59)
Nguyen: 5.75" (0.55)
**Overall ~5.2" (0.55)**
* Middle East
Hussein: 4.96" (0.75)
Kamel: 5.08" (0.75)
Awwad: 5.35" (0.67)
Chen: 5.35" (0.67)
Shalaby: 5.45" (0.53)
Soylemez: 5.5" (0.62)
Habous: 5.63" (0.79)
Habous: 5.65" (0.73)
Salama: 5.91" (0.71)
Salama: 5.9" (0.59)
**Overall ~5.5" (0.69)**
* West
Acuna: 5.47" (0.67)
Khan: 5.63" (0.66)
Schneider: 5.7" (0.78)
Gabrich: 5.7" (0.63)
Stewart: 5.9" (0.67)
Pereira: 5.96" (0.83)
Wessels: 6.2" (1.03)
Barboza: 6.32" (0.64)
Vasconcelous: 6.54" (0.67)
Bondil: 6.59" (0.9)
**Overall: ~6.1 (0.78)**
Here we can see that Asian studies on average have lower results and variance than Middle Eastern studies, and those have lower averages and variance than Western studies.
3 SD above average - which is about 1 in 1000 - would be 6.9" in Asia, 7.6" in the Middle East and 8.4" in the West
That's also something that's shown in those studies. 7" are incredibly rare in studies from the East, but relatively common in studies from the West.
Even in small Western studies there's always high max values (e.g. 8.5" in a sample of 80, 10.7" in a sample of 905), but even in large Asian studies there's barely any big dicks.
Here's two examples to highlight this further:
Chen:
https://www.nature.com/articles/ijir20149
Among 5196 Chinese men the average was 5.1" and the largest was 6.7". Not a single 7 incher in such a huge sample, even though in Western studies more than 1 in 10 guys are this size
Pereira:
Estudo do Tamanho do Pénis na População Portuguesa
During mandatory military screening they measured 19 random Black Portuguese men and found an average of 6.9" (the Black subgroup was nearly an inch longer than the overall average of the study). Even though it was such a small sample they still managed to find one with 8.5"
Most Black guy in this small sample were larger than the largest Chinese guy in a sample of over 5000 while the smallest Black guy in this sample was still larger than the average Chinese guy.
If we assume that there's no racial differences these would have been two extremely rare random occurrences.
Let's assume that there's no differences and that 7" is about top 1% globally.
In order for Chen not to find any 7 incher that's (1 - 0.01)^5000 which is like 1.5 * 10^-22 - that's an incredible low chance
In order for Pereira to find an average of 6.9 inches that's like 0.02^19 which again is an incredibly low chance at around 5 * 10^-33
It's more likely that you'll win the lottery several times in a row. If you let two people pick a random grain of sand from all sand on earth there's a higher chance that they'll pick the exact same grain rather that those studies randomly came across those numbers.