Thanks for the answer ! So if I understand everything, I should do a lot of assets and differents versions of this (like inferior arch 01, 02, wall 01, 02… with some sculpts and textures variations) and after this, import everything separatly in unreal to create some groups like my first picture ? (like this one : Gladiator's Arena - Making of – part 1 · 3dtotal · Learn | Create | Share )
And then, can I do a circular array of this differents groups ? (or array + bend like in blender) I found nothing about this on google or unreal guide.