See the following article for how to apply this to your project:
https://docs.kicad.org/6.0/en/pcbnew/pcbnew.html#custom_design_rules
JLCPCB capabilities reference:
https://jlcpcb.com/capabilities/Capabilities
TL;DR: I cannot guarantee that this is 100% correct. There may be bugs or outdated information, and you are ultimately responsible for ensuring that it meets your requirements.
That being said, if you do find any issues with this script, please let me know so it can be fixed!
Long form:
Affirmer offers the Work as-is and makes no representations or warranties of any kind concerning the Work, express, implied, statutory or otherwise, including without limitation warranties of title, merchantability, fitness for a particular purpose, non infringement, or the absence of latent or other defects, accuracy, or the present or absence of errors, whether or not discoverable, all to the greatest extent permissible under applicable law.