Copy-pasting with minor changes used to be a common practice among students for their academic assignments in the past. However, things are completely changed now as you can’t do it even if you do it smartly.
You might have to prove that you did not copy and paste your assignment or some parts of the assignment. The best way to prove authenticity is to keep a record of everything you have worked on. For example, you can take the following measures:
In short, you should keep all the records in place unless your assignment has gained full acceptance by your teacher. On the contrary, if you hire an assignment service, it may not be possible to ask them evidence.