To make such code you have to have some idea about debugging and assembly and it's not always possible.
Hoewer there are such codes for FFXII NTSC-U which makes it very easy to just recreate them for any other FFXII version;].
In cheat engine set search range for EE memory which is 20000000-21FFFFFF, then uncheck "writable" as that code isn't there;]. Then make an aob scan for "12 A8 00 00 13 00 20 12" for exp multiplier, if it doesn't give any result, try searching for just 4 bytes hex 0x0000A812, just use the values from NTSC-U codes to set multiplier. For LP search for this array of bytes "2D 10 60 00 ?? ?? ?? ?? 2D 10 60 00" and change both the adress from the result and the one 8 bytes after it same way just like with NTSC-U codes.
Code:
//exp multiplier
//x1 - disable code
patch=1,EE,203B6BC4,extended,0000A812
//2x
patch=1,EE,203B6BC4,extended,0002A840
//4x
patch=1,EE,203B6BC4,extended,0002A880
//8x
patch=1,EE,203B6BC4,extended,0002A8C0
//16x
patch=1,EE,203B6BC4,extended,0002A900
//32x
patch=1,EE,203B6BC4,extended,0002A940
//lp multiplier
//x1 - disable code
patch=1,EE,203B6D2C,extended,0060102D
patch=1,EE,203B6D34,extended,0060102D
//2x
patch=1,EE,203B6D2C,extended,00031040
patch=1,EE,203B6D34,extended,00031040
//4x
patch=1,EE,203B6D2C,extended,00031080
patch=1,EE,203B6D34,extended,00031080
//8x
patch=1,EE,203B6D2C,extended,000310C0
patch=1,EE,203B6D34,extended,000310C0
//16x
patch=1,EE,203B6D2C,extended,00031100
patch=1,EE,203B6D34,extended,00031100
//32x
patch=1,EE,203B6D2C,extended,00031140
patch=1,EE,203B6D34,extended,00031140