NoSt140,820 25 Nov 2020 03 Dec 2020 03 Dec 2020
This achievement should be pretty easy as the EXP cap in BGII: Enhanced Edition is 8,000,000 and you only need 4,400,000 to reach level 30.
Still I'd recommend not to use a dual class or a multiclass to be certain that you reach level 30 before you reach the EXP cap.