Ah ok it is in the "advanced settings" menu ☺ It worked for games (especially sega mster system ones, because of the intermediate resolution these had) but terminal still no way 😞

Edit: another solution may be to change manually overscan as the wiki reads:
https://github.com/recalbox/recalbox-os/wiki/Overscan-settings-(EN)

and see what happens...but since in terminal recalbox provide only vi and vim (i always used nano) and most of all i'm a complete nood i dout gonna try since don't wanna mess with the system ;( well other ideas are more than welcome!

May custom overscan be in the future set in emulation station? Would be great, thanks anyways!!