Screenrant answered it pretty well:

Earth 89: Tim Burton's Batman Movies

Tim Burton's Batman films are represented in one quick cameo, which confirmed it as Earth-89. Danny Elfman's familiar Batman theme plays as the Bat-Signal burns bright in the red skies over Gotham City. This is observed by a man in a trench-coat and fedora, who mutters "I hope you're watching, big guy." The observer is reporter Alexander Knox (Robert Wuhl), who was the first to report upon The Joker's crimes in the 1989 Batman movie.

_{Alexander Knox above}

Earth 9: DC Universe's Titans

We briefly see red skies over Titans Tower in San Francisco, before being treated to close-ups of a disturbed looking Hawk (Alan Ritchson) and an upset Jason Todd (Curran Walters).

_{Jason Todd aka Robin (Curran Walters) and Hawk (Alan Ritchson)}

Earth 66: 1966 Batman TV Show

One of the first cameos confirmed for Crisis on Infinite Earths was Burt Ward, who played the Dick Grayson Robin on the 1966 live-action Batman series alongside Adam West's Batman. Ward's cameo is short and sweet, as we see Dick Grayson walking a dog while wearing a red sweater with yellow and green trim suggesting the classic Robin costume. Suddenly, the skies turn red and sinister, prompting the former Boy Wonder to shout "Holy Crimson Skies Of Death!" It isn't a big scene, but it is enough to confirm the 1966 Batman show as the Earth-66 of the Arrowverse.

_{Dick Grayson Robin(played by Burt Ward)}

Other Earth's you might already know, which are:

Earth 1:

Flash, Arrow, and Batwoman related characters live here.

Earth 38:

Supergirl's universe.

Earth X:

With the Ray, evil Arrow and Supergirl, part of older crossover.

Earth 16:

Jonathan Kent (Superman's son) landed there by mistake. And it was prominently featured before in Legends of Tomorrow season 1 with a dark future of Earth 1 heroes in 2046.

Earth 2:

Mentioned by Oliver (didn't appear) which got destroyed in Arrow season 8 with a single survivor Laurel Lance.

Unknown Earth:

Nash Wells aka Pariah belongs to this Earth, he freed the Anti-Monitor. His Earth does not appear nor is it mentioned directly or numbered yet.

From Crisis: Episode 2 (Batwoman)

Earth 74:

Legends of Tomorrow have retired and Mick Rory is left inhabiting the Waverider

Earth 99:

Batman (Kevin Conroy) has retired and can only move thanks to an exoskeleton.

Earth 75:

Superman of this Earth is killed by Lex Luthor wielding the Book of Destiny

Earth 167:

Superman (Tom Welling) has given up his powers and is now living with his family Lois Lane (Erica Durance) and his daughter on the Kent farm.

Earth 96:

Superman (Brandon Routh) as Clark Kent is Editor in Chief of the Daily Planet

Earth 18:

Location of the Lazarus Pit. (with Jonah Hex cameo)

From Crisis Episode 3 (The Flash)

Earth 203

New Gotham with the Birds of Prey

Earth 666

Lucifer's Earth (Tom Ellis)

Earth 90

Earth of the Flash (John Wesley Shipp)

Earth (not stated)

Earth of Black Lightning

From Crisis: Episode 4 (Arrow) & Episode 5 (DC's Legends of Tomorrow)

Earth-2

Previously destroyed, now home to the Justice Society of America & Stargirl (new CW series in course)

Earth-9

Home to the the Titans

Earth-12

Home to the the Green Lantern Corp - possible reference to Green Lantern tv series on HBO-Max

Earth-19

Home of The Swamp Thing

Earth-21

Home to Doom Patrol

Earth-96 (rebooted?)

Brandon Routh is Superman

Earth-96 was inspired equally from the first five Superman movies and the classic graphic novel Kingdom Come. It was named in honor of the year in which Kingdom Come was first published - 1996.

Earth-Prime

Previously Earth-1, now apparently a combined Earth which is home to:

• The Flash
• Supergirl
• DC's Legends of Tomorrow
• Batwoman
• Black Lightning - may previously have been Earth-1
• Superman & Lois - new CW series in course