I don't know how this font is encoded, but it's often the case in modern fonts that variant glyphs are mapped to the same code point (i.e. U+0030 in this case) so you can't directly type the variants. If you want to use them then your software needs to understand how to select font features.

In CSS you can use font-feature-settings.

https://developer.mozilla.org/en-US/docs/Web/CSS/@font-face/...