If you run KiCad 5.99 which was build including the new Plugin and Content Manager (using the compile option -DKICAD_PCM=ON), you can simply add the repository url and install the themes inside KiCad: ...
KiCad has the ability to render the PCB in 3D, which helps the mechanical design of the enclosure. Unfortunately, KiCad's 3D model management is a mess. KiCad separates the schematic symbol library ...