Direct connection between an SD card reader to an ESP8266 sans logic shifters

You only need level shifters if your processor runs at 5V, as the SD card runs at 3.3V - if your processor runs at 3.3V then there's no need for a level shifter.

As you're using an ESP8266, which is 3.3V only, then no level shifter needed. Other devices, such as PIC's and AVR's, can often be used on either 5V or 3.3V, so you need to ensure you run them on 3.3V, or add a level shifter.

SD card modules only come with level shifters if you specifically order that type - most don't, and are just a plain SD socket.

Order the ESP32 with the included microSD card slot and you have no worries, no work and better, less noisy connections.