child theme?

I haven’t updated my wp version in over a year because I don’t have child theme and someone told me I will lose certain changes if I don’t first add a child theme. I honestly don’t have a clue about coding, and I’ve asked here but didn’t get an answer.

2 questions;

how much would it cost for someone to write a child theme for me?

alternatively, would a plug-in like Child Theme Configurator solve my problem?