In the early days of his channel, Isaac needed a way to make his videos stand out in a sea of overly polished YouTube thumbnails. Instead of downloading a generic, thick lettering font from a free site, he grabbed his drawing tablet and started writing the titles himself.
While the full "Heavy" version is often paid, similar bold, geometric sans-serifs can be found on sites like Google Fonts (e.g., Montserrat or Archivo Black) or apply similar styling isaacwhy font
Because is a core system font on Windows (and usually converts to "Impact" on Mac in Office suites), you likely already own it. However, if you are on a Mac and cannot find it: In the early days of his channel, Isaac