At first sight, I thought the textures represented tiles, not bricks or stone blocks, because of the highly visible central edge of the pillar that makes sense only with tiles separately applied to the two sides.
But tiles are neither curved (left intrados) nor cut in fancy concave shapes (upper walls), they are usually aligned or staggered along the major axis, not the minor one (walls and pillar), and they are usually all the same size (not three or more: walls, pillar, upper walls, variants).
Imagine how this structure would be made with normal bricks or stone blocks, using historical buildings as reference. Your geometry and textures could become far more complex (individual shaped blocks, curved bands of rectangular bricks with wedge-shaped mortar layers between them, etc.) but plausible.
JoeJ's suggestion to literally plaster over these complications is both effective and realistic: you can keep simple geometry (up to a point; some decorations should be expected) and paint walls ornamentally.