I'm a big fan of "Avatar: The Last Airbender." Because of that, I was surprisingly reluctant to watch this four-years-on sequel - what if it wasn't as good? But finding it on Netflix during the pandemic was enough of a push that I starting watching it. (Although it should be noted Netflix have only two of the four seasons. This isn't as bad as it sounds, as each season is a complete storyline - a feature I appreciate.)
This series started airing in 2012, four years after the previous series ended - but it's set 70 years after the events of the previous series. And they seem to have gone with the same target audience: kids who were 11 for the original and would now be 15, and ready for more morally complex story lines. They've also changed the society shown in the series a lot: they were pre-technological (except for the evil Fire Nation, who had some "technology"), but their world now has the technological equivalent of our Earth around 1930. A couple forms of bending considered extreme in the previous series (lightning and metal bending) are now relatively commonplace - and bending has become a common part of society, another form of work. It's a big change, and a well thought-out one.
On top of this they heap politics, more of the hatred we occasionally saw in the previous series, extremism, and terrorism. And personal relationships are shown as being more complicated: one man is shown as being torn between two women. These things are handled slightly reductively, this being a teens show, but once again the series doesn't talk down to its viewers. It just puts this stuff out there, and says "life is complicated: you do the best you can."
I'm conflicted about how to describe this series. "Korra" couldn't exist without the original "Avatar." "Korra" is more complex, with less obviously child-simplified plots. It's really interesting and really good. But at the same time, one of the great virtues of the original series was its relative simplicity. In the end, its a brilliant addition to an already extensive mythology.