Can I Do Customization In Sytist

 i need customize register page and i need user photo recognition using AI can i do this in you sytist. also i need to change email message and i need to add one filter in gallery listing page can i do?

There is no AI photo recognition in Sytist and you can't just add one.

You can change email messages in Settings -> Default Messages.

I don't understand your other questions.

using custom code can i do in my website ?

You can not modify the files to add your own custom code.

i need to add custom code in register page only can i do this one in pro version because i check you are using php for this websites and i need to edit this register page using php

What do you need to add to the register page?

in register page i need to add user can add their photo and video

That is not something you can add. 

There is no feature for people to upload their own images. 

You won't be able to do that with Sytist and it is against the terms and conditions to modify the code.

can you please share the term and condition that you specified.