The story possibilities for "And Just Like That" season two are pretty wide open at this point. It's likely Carrie will continue single life after losing Big, but it would be interesting to see her find love again. The first season does end with her smooching her podcast producer, Franklyn, so perhaps we'll see if this new connection gets some expansion in the second season.
When it comes to Che and Miranda, it's a bit of a mixed bag. The first season ends with Miranda giving up an important internship to go support Che's pilot in Los Angeles. Due to how polarising Che was, it would be interesting to see if writers adjust the character to be more likable. On the flip side, Miranda might also realise that LA isn't for her and head back to her old life and friends in New York City. There's a lot to work with here!
And lastly, there's Charlotte. The first season explores Charlotte's relationship with her children, most notably her coming to terms with Rock's gender identity. Perhaps we'll see more of this get fleshed out in the second season of "And Just Like That."