Plagiarism of Code/How to check

One student, who had some previous experience, went way beyond the requirements of the task in Unit 5 Lesson 3. I suspect that he copied code from somewhere. Is there a way to check for “code plagiarism?”

Would this website work for you?

https://codequiry.com/

It seems that this site costs $25 per month. Do you know of a free site?

No. I did a quick google search and that was what came up on another forum as a highly recommended resource.