So they used to do this but a lot of high profile people got banned for being flagged as real world traders by jagex when they were actually just swapping gold between osrs/rs3. Because of this jagex hasn't rlly done many bans for simply trading gold to an account, due to the high chance of it simply being swapping, which isn't against the rules. And when i say "jagex hasn't rlly done.." i mean there haven't been any high profile cases anybodys mentioned since then. That being said, there have been mules banned in the past by like mod weath but those mules are almost always MASSIVE gold farmers.
I've said this before on some other posts, but if you're a small scale gold farmer you shouldn't be too scared about getting things like mules banned because jagex has much bigger fish to fry than to waste time on someone only trading like 1b, especially because swaps are so common with amounts like 1-3b rs3.The conventional methods should work fine for small scale gold farms. Idk if u meant rs3 or osrs but 1.2b is small for rs3 so you should be fine trading that over to a mule. If you wanna be safe just do it in 2 trades of like 500m or so over like 3 days.