Transit visa. I have italian nationality and

I am going from Malaysia to Mexico
Thru 2 Chinese cities
Kuala Lumpur > Shenzhen
Then I need to check in again in Shenzhen
For a new flight
Shenzhen > Chongqing Jiangbei
And then I need to check in again in
Chongqing Jiangbei
For a new flight
Chongqing Jiangbei > Los Angeles
Do I need
Transit visa

Or I can just receive free transit 24h at the Chinese airport
Thank you