Are all eukaryotic cells found in large animals?

At the highest level of biological classification, there are three "Domains": Bacteria,Archaea, and Eukarya.

Bacteria and Archaea are prokaryotes - but Eukarya are Eukaryotes.

Eukarya contains four "Kingdoms": Animalia, Plantae, Fungi and Protista.

Animalia is all animals, plantae is all plants, fungi is all fungi, and protista is single-celled eukaryotes (like amoebae, paramecia, euglena, etc.)

So while all large animals are made of eukaryotic cells, not all eukaryotes are animals.