Q: Is it possible to transfer photos from ipad to the sd card????

You should be importing all photos to your computer.  From your computer, you can do whatever you like with them

Also, I believe that there is an iPad camera accessories that has a card reader.

The SD card accessory can only read and download images to your iPad. It still cannot upload images to the card through the accessory.

Something like this from SanDisk maybe of interest to you.

https://www.sandisk.com/home/mobile-device-storage/connect-wireless-stick