Hey Suraj,
What Andi says is right. If you use my EAs on your broker’s data, just check if they do well. After that place them on a Demo and see which are the top performers. The OOS is useful when we generate new EAs.
Walk forward is a fantastic robustness tool but again when generating the EAs.
Simply, when you have ready EAs, all you need to do is to test them and decide which ones to place on a live account.