It's not too late but only if the big players make the right changes very soon.
COP26 is proving itself to be a complete waste of time, just look at the headline saying lots of countries have committed to phasing out coal, except India, the US and the Chinese. The three countries that have the biggest impact won't do it.
We need to address the real problem which is overpopulation. The trouble is there is no particular will to do this because campaigners fear they will be called racists or worse for promoting it. They prefer to say "it's not the number of people, it's the disproportionate use of resources" that's the problem.
Bull-fucking-shit. More people use more resources, end of. Maybe ten Americans use the same resources as a hundred Ethiopians (I'm making that number up by the way). So what? Ten Americans and a hundred Ethiopians use more resources combined than five Americans and fifty Ethiopians would. It's so obviously true, it's rather insulting to the intelligence to argue otherwise.
We need drastic population control, now. This means limiting the number of children people have to one per person (i.e. a father can have one child with one woman and vice-versa). If you have a second, you are imprisoned and sterilised. Obviously with exceptions for twins etc.
The trouble with a reasonable policy like this is that it could never be enacted. Even if one country agrees, the biggest countries won't. Maybe the answer is to impose sanctions on countries that don't comply - if we could get the UN to enforce this it might just work. End aid to India, prevent China exporting goods, things that would damage their economies in the same way we do for North Korea.
Actually, the OP's right - it is too late. It was always "too late" because humans can't adopt policies as a whole species. We're brought up to accept and celebrate our differences and what makes us unique. What is rational to one group is highly offensive and unfathomable to another.
"Let the world burn" seems like the most sensible advice. Enjoy what time we've got left, live for today, after all 2100 is well beyond most of our lifetimes.