To use custom font in Astro, you can follow their documentationto register the font as below:

    @font-face {
    font-family: 'DistantGalaxy';
    src: url('/fonts/DistantGalaxy.woff') format('woff');
    font-weight: normal;
    font-style: normal;
    font-display: swap;
    }

If your font is a .ttf, and you change the code to format(‘ttf’) it will not work. Should be format(‘true type’)