Yes there are various courses available of diploma in child Psychology offered by different organisations to the students in online mode. I am mentioning below the name of some websites which offer child Psychology diploma courses to the students:

• Udemy
• Alison
• Nhca

Other than this now I am mentioning below the name of the courses at diploma level in online mode which are han of duration from 1 to 2 years:

• Post graduate diploma in guidance and counselling
• Advanced diploma in child guidance and counselling
• Diploma in counselling psychology
• PGD in guidance and counselling
• Diploma in psychology assistance

Read more about  Psychology process by clicking on mentioned below link:

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.careers360.com/courses/psychology-course&ved=2ahUKEwjJtMvswKv1AhXadd4KHZYQDnkQFnoECAoQAQ&usg=AOvVaw0mQrQmigxXxzmzT9WOyDj7