There are the national enquiries which were mentioned earlier, although sadly as others have also pointed out with regards to Grenfell, Hillsborough, and so many more, I suspect the end result will be the usual government lip service "Lessons have been learned, blah, blah, blah".
And then there'll be another earth-shattering event (certainly climate change, at some point) and all those so-called leaders will behave in exactly the same way.
Already in my circle there's a suggestion that some people are talking about how we all banded together and banged pots and wasn't it all wonderful, while others are focusing on the appalling loss of life and suffering; no two people had the same pandemic. (I do work in backroom healthcare and have a lot of nursing/medical relatives and friends, though, so that has probably also helped shape my response.)
COVID-19 has been a generational global shock, and its true effects probably won't be understood for at least a generation or so. There's a theory called inter-generational trauma which suggests that the effects of major upheavals like this actually show themselves in later generations.
Personally I've always kept journals since I was 13, in an attempt to make some sense of this bonkers world we all find ourselves in, and I found during the COVID-19 pandemic my journal keeping was so sporadic as it was just too much. I have a whole file saved online of some of the truly astonishing newspaper articles about things that happened from the end of 2019 through to last autumn, both good and bad. For me, the whole situation also highlighted just how rubbish and self-serving our so-called leaders are, globally, with a handful of honourable exceptions - it's only now starting to come out. Far better to rely on family, friends, found family, decent colleagues if you can.
There are no rules - we all process things differently, hope you find something that will work for you.