You will find available for sale round posts for mesh and rectangular profile posts, mainly for fence panel spans.
Each type of post is available in both sides galvanized or with double corrosion protection, i.e. GALVANIZED+ powder coating. Powder-coated posts come in 4 basic colors that are used in fences, i.e. green, graphite (anthracite), black and brown.
If you have a concrete substrate (concrete, cube, asphalt), then apply the base to the pole, which you will screw to the concrete, and on the base you will plant a stable post.