Tilemap.SetEditorPreviewTile

public void SetEditorPreviewTile (Vector3Int position, Tilemaps.TileBase tile);

Parameters

position	Position of the editor preview Tile on the Tilemap.
tile	The editor preview Tile to be placed the cell.

Sets an editor preview tile given the XYZ coordinates of a cell in the tile map.

The editor preview tile is used for previewing possible additions to the tile map.