Sorry, Visual Assist only works with regular VC++ projects (i.e. Embedded Project Wizard) and not with advanced projects such as the new ESP-IDF project type, as those projects are not based on VC++ and Visual Assist does not know how to attach to them.
You can use the regular Tools->Options->Environment->Fonts and Colors to modify the syntax highlighting colors for both regular C/C++ and VisualGDB-based projects.
If you are missing some fine-grain highlighting rules/settings, please feel free to let us know. The code highlighting for ESP-IDF projects is fully managed by VisualGDB, so we might be able to add a few extra cases there as long as it doesn’t require a major change on our side.