JLCPCB Design Rules for KiCad 7.0, implemented as Custom Rules in PCB Editor File > Board_Setup... > Design Rules > Custom Rules), and stored in the .kicad_dru file.
These rules use some features only available in KiCad 7.0.
Each design rule is validated for PASS/FAIL the associated PCB (.kicad_pcb).
Simply copy the JLCPCB.kicad_dru file into your KiCad 7 project folder, and rename it to match your project name your-project.kicad_dru.
The JLCPCB Design Rules will automatically be included in the KiCad PCB Editor (File>Board Setup...>Design Rules>Custom Rules), and be included when performing a Design Rules Check (DRC) (Ìnspect>Design Rules Checker).