How to use the tailwindcss/defaultTheme.borderWidth function in tailwindcss

customForms: (theme) => ({
      default: {
        'input, textarea, select, multiselect, checkbox, radio': {
          borderWidth: defaultTheme.borderWidth[2],
          '&:focus': {
            outline: 'none',
            boxShadow: 'none',
            borderColor: theme('colors.brand.primary'),
          },
        },
      },
    }),
    spinner: (theme) => ({

zIndex: {
      auto: 'auto',
      '0': '0',
      '10': '10',
      '20': '20',
      '30': '30',
      '40': '40',
      '50': '50',
    },
    customForms: {
      horizontalPadding: defaultTheme.spacing[3],
      verticalPadding: defaultTheme.spacing[2],
      lineHeight: defaultTheme.lineHeight.normal,
      fontSize: defaultTheme.fontSize.base,
      borderColor: defaultTheme.borderColor.default,
      borderWidth: defaultTheme.borderWidth.default,
      borderRadius: defaultTheme.borderRadius.default,
      backgroundColor: defaultTheme.colors.white,
      focusBorderColor: defaultTheme.colors.blue[400],
      focusBoxShadow: defaultTheme.boxShadow.outline,
      boxShadow: defaultTheme.boxShadow.none,
      checkboxSize: '1em',
      radioSize: '1em',
      checkboxIcon: `<svg xmlns="http://www.w3.org/2000/svg" fill="#fff" viewBox="0 0 16 16"><path d="M5.707 7.293a1 1 0 0 0-1.414 1.414l2 2a1 1 0 0 0 1.414 0l4-4a1 1 0 0 0-1.414-1.414L7 8.586 5.707 7.293z"></path></svg>`,
      radioIcon: `<svg xmlns="http://www.w3.org/2000/svg" fill="#fff" viewBox="0 0 16 16"><circle r="3" cy="8" cx="8"></circle></svg>`,
      checkedColor: defaultTheme.colors.blue[500],
      selectIcon: `<svg fill="${
        defaultTheme.colors.gray[500]
      }" viewBox="0 0 24 24" xmlns="http://www.w3.org/2000/svg"><path d="M15.3 9.3a1 1 0 0 1 1.4 1.4l-4 4a1 1 0 0 1-1.4 0l-4-4a1 1 0 0 1 1.4-1.4l3.3 3.29 3.3-3.3z"></path></svg>`,
      selectIconOffset: defaultTheme.spacing[2],
      selectIconSize: '1.5em',
    },

customForms: (theme) => ({
      default: {
        'input, textarea, select, multiselect, checkbox, radio': {
          borderWidth: defaultTheme.borderWidth[2],
          '&:focus': {
            outline: 'none',
            boxShadow: 'none',
            borderColor: theme('colors.brand.primary'),
          },
        },
      },
    }),
    spinner: (theme) => ({