Upload custom font files
Do you have a custom theme? If so, you can implement it like this:

Place your fonts in your custom theme, following something similar to this folder structure:

themes
  custom
    my_custom_theme
      fonts
        my_font.woff2
        my_font.ttf
        my_font.svg


And then in your CSS file (it might be in themes/custom/my_custom_theme/css/style.css for example) add the following:

@font-face {
  font-family: "my_font;
  src: url('/fonts/my_font.woff');
  src: url('/fonts/my_font.ttf');
  src: url('/fonts/my_font.svg');
}