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Jk, here's the one line summary from Wikipedia:
The story follows an orphaned young girl, Riko, who finds and befriends a humanoid robot Reg and descends with it into the titular "Abyss", that leads deep into the Earth, in hopes of finding her mother. If you have Amazon Prime, you can watch it here free of additional charge!
A curated list of stuff I've enjoyed:
Made in Abyss
Houseki no Kuni
Full Metal Alchemist: Brotherhood (dubbed)
Darker Than Black (dubbed)
Kara no Kyoukai
Koi to Uso
Ergo Proxy (dubbed)
Fune wo Amu
Mushishi 2014 and 2006
Puella Magi Madoka Magica
Spice and Wolf
Hey Yoringe, you should watch MADE IN ABYSS
Which country are you in?
I see it on VRV/HiDive: https://vrv.co/series/G6W4M3V0R
and Amazon: https://www.amazon.com//The-Edge-of-the-Abyss/dp/B073S2MKR2
And found via because.moe search.
Either here or here.
You could also buy the blurays.
The best series that fits what you're looking for is on Amazon.