Create the script
Save this as scripts/runtime_block.aeo:
const block = cell.new("Block")
block.position = [5, 2, 5]
block.color = [1, 0.5, 0]
This code runs at script startup. It does not need an object binding.
Test
Start Play and look near [5, 2, 5]. The orange Block should appear. Adjust the coordinates if that position is hidden by your World.
Remove it
Call cell.delete(block) while the handle is valid, or stop Play. The Block is not added to your saved World.
See Cells and cell.new().