Expanding Force is learned by 1 species by level, 61 by machine and 63 by tutor

Effect, in PokéAPI's words

“If Psychic Terrain is active and the user is grounded, this move hits all opposing Pokemon and has its power incrased by 50%.”

Who learns it

84 species in all, 2 games

Scarlet and Violet: 61 species

Species	Method	Level
Armarouge	Level up, Machine	56
Wigglytuff	Machine
Slowpoke	Machine
Slowbro	Machine
Drowzee	Machine
Hypno	Machine
Exeggutor	Machine
Mewtwo	Machine
Mew	Machine
Espeon	Machine
Slowking	Machine
Girafarig	Machine
Ralts	Machine
Kirlia	Machine
Gardevoir	Machine
Meditite	Machine
Medicham	Machine
Spoink	Machine
Grumpig	Machine
Chimecho	Machine
Metang	Machine
Metagross	Machine
Jirachi	Machine
Deoxys	Machine
Bronzor	Machine
Bronzong	Machine
Gallade	Machine
Uxie	Machine
Mesprit	Machine
Azelf	Machine
Cresselia	Machine
Gothita	Machine
Gothorita	Machine
Gothitelle	Machine
Solosis	Machine
Duosion	Machine
Reuniclus	Machine
Delphox	Machine
Espurr	Machine
Meowstic	Machine
Inkay	Machine
Malamar	Machine
Hoopa	Machine
Oranguru	Machine
Bruxish	Machine
Solgaleo	Machine
Lunala	Machine
Necrozma	Machine
Hatenna	Machine
Hattrem	Machine
Hatterene	Machine
Indeedee	Machine
Calyrex	Machine
Wyrdeer	Machine
Rabsca	Machine
Espathra	Machine
Veluza	Machine
Farigiraf	Machine
Scream Tail	Machine
Iron Valiant	Machine
Iron Crown	Machine

Sword and Shield: 63 species

Species	Method	Level
Wigglytuff	Tutor
Kadabra	Tutor
Alakazam	Tutor
Slowpoke	Tutor
Slowbro	Tutor
Exeggutor	Tutor
Starmie	Tutor
Mr. Mime	Tutor
Jynx	Tutor
Mewtwo	Tutor
Mew	Tutor
Natu	Tutor
Xatu	Tutor
Espeon	Tutor
Slowking	Tutor
Celebi	Tutor
Ralts	Tutor
Kirlia	Tutor
Gardevoir	Tutor
Baltoy	Tutor
Claydol	Tutor
Metang	Tutor
Metagross	Tutor
Jirachi	Tutor
Bronzor	Tutor
Bronzong	Tutor
Gallade	Tutor
Uxie	Tutor
Mesprit	Tutor
Azelf	Tutor
Cresselia	Tutor
Victini	Tutor
Munna	Tutor
Musharna	Tutor
Woobat	Tutor
Swoobat	Tutor
Darmanitan	Tutor
Sigilyph	Tutor
Gothita	Tutor
Gothorita	Tutor
Gothitelle	Tutor
Solosis	Tutor
Duosion	Tutor
Reuniclus	Tutor
Elgyem	Tutor
Beheeyem	Tutor
Espurr	Tutor
Meowstic	Tutor
Inkay	Tutor
Malamar	Tutor
Oranguru	Tutor
Solgaleo	Tutor
Lunala	Tutor
Necrozma	Tutor
Blacephalon	Tutor
Dottler	Tutor
Orbeetle	Tutor
Hatenna	Tutor
Hattrem	Tutor
Hatterene	Tutor
Mr. Rime	Tutor
Indeedee	Tutor
Calyrex	Tutor