ESP32 allows to assign almost any functionality (SPI, I2C, etc.) to almost any GPIOs.

Using the example GxEPD2_WS_ESP32_Driver.ino from the GxEPD2 library with the following GPIO setup worked for me. (Note: I used a Waveshare 2.9" ePaper for my test.)

• DI <--> 26
• SCK <--> 18
• CS <--> 21
• DC <--> 22
• BUSY <--> 32
• RESET <--> 33

On line 118 of the example you set the GPIOs for CS, DC, RST and BUSY:

GxEPD2_DISPLAY_CLASS<GxEPD2_DRIVER_CLASS, MAX_HEIGHT(GxEPD2_DRIVER_CLASS)> display(GxEPD2_DRIVER_CLASS(/*CS=*/ 21, /*DC=*/ 22, /*RST=*/ 33, /*BUSY=*/ 32));

On line 150 of the example you set the GPIOs for SPI:

  SPI.begin(18, 36, 26, 21); // map and init SPI pins SCK(18), MISO(36), MOSI(26), SS(21)

Thanks
Felix