No actually. If you consider the plants to be Archaeplastida (glaucophytes, red algae, and Viridiplantae) or Viridiplantae (the green algae including Embryophyta) then the common plant ancestor is unicellular (greens and reds evolved multicellularity independently). If you consider the plants to just be Embryophyta (the land plants) then they already had highly specialized cells and looked plant-like before they split off from the rest of the green algae.

I'm not sure if the fungal common ancestor is believed to have been unicellular or multicellular but if it was multicellular then it would've been filamentous like modern multicellular fungi, rather than a sheet of cells