I am using a ESP32-LoRa board with an OLED. It is made by Heltec. It uses the library called "Heltec_ESP32_Dev-Boards".
Its documentation says:
setFont sets the current font. Available default fonts:
ArialMT_Plain_10, ArialMT_Plain_16, ArialMT_Plain_24.
Or create one with the font tool at http://oleddisplay.squix.ch.
Syntax: void setFont(const uint8_t fontData);*
If you go to the mentioned website, it will generate the code to put into a .h file defining a specific font. But I don't know how to make my own file. I want to make a font that they do not have.