org-bullets VS victor-mono

I use the Modus Vivendi theme, FiraCode as my font, and org-bullets for styling. My headings are easily distinguishable across the levels in this set-up.

That's normal. The fancy dots come from the package Org-bullets. Different sized headings are usually theme dependent, I'm not sure off the top of my head which of the doom themes support them though. As for the built in themes, I know that the Leuvan theme supports them, and the Modus themes do as well. It's also very possible there is a variable which dictates the behavior of the org headings. I would use the built in help to search for a variable with a name along the lines of org headings or org height, something like that. You can access the help with M-x describe-variable or with the regular emacs keybindings (sorry I'm not an evil user) C-h v

You probably want something like this:https://github.com/sabof/org-bullets

That's not a trick question. Victor Mono does support ligatures.

Used FiraCode for a while, then switched to Victor Mono [0], but found myself going back to Cascadia Code [1]. I can't seem to be able to get along with fonts that are too thin it seems.

[0]: https://rubjo.github.io/victor-mono/

The font is called VictorMono!

I don’t know about the one from your screenshot, but I use Victor Mono https://rubjo.github.io/victor-mono/

I don't use ligatures at all, but I have seen it on websites. So perhaps it's the CSS of the website that has decided to do this. I don't have any specific examples off hand, but my mental picture puts it on sites that also use this style of font: https://rubjo.github.io/victor-mono/ (although typing fi into the sandbox on the site doesn't exhibit the behavior).

like here: https://rubjo.github.io/victor-mono/

Previously, [VictorMono](https://rubjo.github.io/victor-mono/), but now I am rocking: [JetBrainsMono](https://www.jetbrains.com/lp/mono/) and [Cascadia Code](https://github.com/microsoft/cascadia-code)