The wireless charger operation is used simply by pressing the “DC” button on the EB70 front panel and placing the device on top of the charger. Some accessory cases may interfere with wireless charging and have to me removed in some circumstances. Your device does of course have to be capable of accepting wireless charging.
I typed “Bluetti EB70” in google and it directed me to the Bluettipower.com website and to the EB70 product which included the link to the EB70. The manual however appears to be the same as the one included with the EB70
The link for the EB70 manual is: https://cdn.shopify.com/s/files/1/0536/3390/8911/files/EB70-Manual-EN.pdf?v=1619170785