Player Options Per Plane:

Zendikar: (Plane Shift: Zendikar)

Races: Name (subrace)
Elves (Tajuru, Joraga, Mul Daya)
Goblins (Grotag, Lavastep, Tuktuk)
Humans
Kor
Merfolk (Emeria, Ula, Cosi)
Vampires

Innistrad: (Plane Shift: Innistrad)

Races: Name (subrace)
Human (Gavony, Kessig, Nephalia, Sternsia)

Backgrounds:
Inquisitor

Kaladesh: (Plane Shift: Kaladesh)

Races: Name (subrace)
Aetherborne
Dwarves
Elves (Bistahar, Tirahar, Vahadar)
Humans
Vedalken

Classes: Name (Subclass)
Sorcerer (Pyromancer)

Amonkhet: (Plane Shift: Amonkhet)

Races: Name (subrace)
Aven (Ibis-Headed, Hawk-Headed)
Humans
Khendra
Minotaur
Naga

Classes: Name (Subclass)
Cleric (Ambition Domain, Solidarity Domain, Strength Domain, Zeal Domain)

Backgrounds:
Initiate
Dissenter
Vizier

Ixalan (Plane Shift: Ixalan)

Races: Name (Subrace)
Goblins
Humans
Merfolk (Green, Blue)
Orcs
Sirens
Vampires

Dominaria (Plane Shift: Dominaria)

Races: Name (Subrace)
Aven
Elves (Wood)
Half-Elves
Humans (Keldon)

Ravnica: (Guildmasters’ Guide to Ravnica)

Races: Name (subrace)
Elves (High, Wood, Dark)
Centaurs
Goblins
Humans
Loxodons
Minotaurs
Simic Hybrid
Vedalken

Classes: Name (Subclass)
Cleric (Order Domain)
Druid (Circle of Spores)

Backgrounds:
Azorius Functionary
Boros Legionnaire
Dimir Operative
Golgari Agent
Gruul Anarch
Izzet Engineer
Orzhov Representative
Rakdos Cultist
Selesnya Initiate
Simic Scientist

Theros: (Mythic Odysseys of Theros)

Races: Name (subrace)
Centaurs
Humans
Leonin
Minotaurs
Satyrs
Tritons

Classes: Name (Subclass)
Bard (College of Eloquence)
Paladin (Oath of Glory)

Backgrounds:
Athlete

Zeal Domain was fairly unbalanced if I remember right....

You could max damage on fire spells (ala Tempest) and got Fireball on the expanded spell list.

You also got the BA strike from War Cleric so you could MC with fighter after you got fireball and wreck house. 

How would we get these options in D&DBeyond?  

Homebrew 'em

List could have at least linked to the Planeshift texts.  Curiously Google doesn't provide a launch page for Plane Shifts maintained by WotC.  However, fandom has MtG wiki and they got links to everything here.  So read 'em and homebrew 'em.