It’s at top right.
If you’re in dark mode like I am, it’s dark grey on black, which makes it hard to see especially on phones.
I don’t think this has come up much. You can get sigil fonts you can download free, but there’s load, and without the original link, it’s hard to tell if this is a font, or a graphic they create. Your best bet is to message the content creator and ask them.
More sigil fonts… sigil like, they’re not sigils obviously it’s the Roman alphabet in code, this is creative fiction.
This site has commercial sigil like fonts just so you get the idea, there’s some cute ones here. I like the Magi one and the Marduck one. The only one that’s really useful is the Morse code one probably.