Hello, You have or can create a field to enter photo in 3x4 format, because as we would have this option in our form?

It is possible to a file upload field to your form and adjust the file size limits.  Here is our quick guide detailing how to increase the limit as well as the maximum file sizes for different integrations:

https://www.jotform.com/help/33-Changing-the-Upload-Size-Limit

You can also change the allowed file types:

https://www.jotform.com/help/29-Upload-Field-Allowed-File-Types

However, it is not possible to limit the upload to specific dimensions.