Canon EOS REBEL T7I Wi-Fi (Wireless Communication) Function Instruction Manual page 104

Sending Images to a Web Service
Sending Images that Match the Search Conditions
Send all the images that match the search conditions set in [Set image
search conditions] at once.
For [Set image search conditions], refer to "Setting Image Search
Conditions" in the Camera Instruction Manual.
104
Press <0>.
1
Select [Send all found].
2
Select [Resize image].
3
Set it as necessary.

On the displayed screen, select an

image size, then press <0>.