Minecraft 1.14

Is it possible to do with an armchair that where he is always executing the fill command that the armor turns the blocks in which he stands in the air is there such a command?

You could execute an / execute command with a commandblock as the armor, and then enter the reative coordinates as the fill area. If you just want to do the one Armorstand, look at it, write the / execute command and then to / execute as press tab then there's such a weird id you take and that's the armory.