The largest scope I have is only to the 10x and the upper end of a variable. Most of my scopes are fixed or variable, with the upper power magnification being 4x, 6x, 8x, 9x or as mentioned 10x.

A 4x scope does everything that is needed on a hunting big game rifle. A 6x adds a bit more.

The modern trend of needing a 16x or a 32x is just because more scopes are made affordable nowadays in such variable.

As for hunting "long distance", do some shooting at say 300 and 400 metres. 400 metres is a long long way away. See how consistently you can hit a 30 cm circle at 400 metres.

If hunting serious big and medium game, anything over 300 metres is a long shot.

A .338 Win Mag is a versatile cartridge to shoot. 225 and 250 gr projectiles for bigger animals. And perhaps some 180 to 200 gr projectiles if you feel the need for lighter bullets for smaller animals.

I would be happy to hunt water buffalo with a .338 using good 250 or 300 gr projectiles.

The cartridge is a one world capable cartridge.