Do I still need to wear a padded jacket in a few days?

No need, currently Jiuzhaigou is more than 20 degrees, and the temperature difference between day and night is not big, so you don’t need to bring it. If you think my answer is satisfactory, please accept it, thank you!

A light jacket is enough. I have short sleeves all the way, and it is very hot when I walk a lot. Depends on whether there is sun on that day

No need, the coldest is no more than a dozen degrees, long johns and fleece are enough.

It doesn't need to be very hot. You can check the weather forecast. The temperature is about the same.