如何解决它 - 更新wordpress中的插件？

I have made modifications in several of the plugins in wordpress. But these plugins are now outdated. I have to submit the project to the client. The client is asking me to update the plugins. But the problem is that when I would update plugins, the changes that I made in plugins would have gone away. So, I want to ask is there any concept of child plugin in wordpress and if so, how to create it; so that my changes would remain intact.I have made modifications in several of the