Wide Scale Terrain

it's even harder to decide Which way or tool to use for building a large scale lands for mobile so is it right to use gaia generator tool or use blender to bulid one big model shapping the landscape or use one big plane with multi shaped mountains created on blender > help me down here to decide whats the best way to bulid large scale land for mobile game Am not A PRO in these things but trying my best Thx.