How to apply variable style fonts?

[xorb]

I have a ttf file which has multiple font styles, bold, regular, semibold, etc.
I am applying this directly to the font created in opentype and it returns the default font (without applying the style), do you know how you can apply or change the fontWeight.

const font = fontsRepository.getOpenTypeFont(styles.fontFamily),
      path = font.getPath(
        char,
        left,
        top + (styles.deltaY || 0),
        styles.fontSize,
      ) as any;

    path.fill = styles.fill as string;
    if (styles.strokeWidth) {
      path.strokeWidth = styles.strokeWidth;
      path.stroke = styles.stroke as string;
    }
    path.backgroundColor = styles.textBackgroundColor;
    path.linethrough = styles.linethrough;
    path.overline = styles.overline;
    path.underline = styles.underline;
    path.fontSize = styles.fontSize;
    path.deltaY = styles.deltaY;
    **path.fontWeight = this.fontWeight;**
    path.strokeDashArray = this.strokeDashArray;
    path.strokeDashOffset = this.strokeDashOffset;
    path.strokeLineCap = this.strokeLineCap;
    path.strokeLineJoin = this.strokeLineJoin;
    path.strokeMiterLimit = this.strokeMiterLimit;

I attach the variable source.
https://fonts.google.com/specimen/Fira+Code