In Neovim, make sure your desired highlight groups have `gui=bold,italic`, e.g.

    hi Comment guifg=#7e7490 gui=bold,italic

In Kitty, set the desired fonts:

    font_family      IosevkaTerm Nerd Font Mono
    italic_font      IosevkaTerm Nerd Font Mono
    bold_font        IosevkaTerm Nerd Font Mono
    bold_italic_font Iosevka Term Slab