How do I change price without having to change individual variants (size and Colours). I want to change the price so one price fits all
You could take a look at an app called Bulk Price Editor/Price Change which will help you to change the price in bulk and they also have a free plan and free trial for you to experience.
I hope this helps.
You can have a look at the T2 Pro Bulk Price Editor app wherein you can bulk edit prices, schedule bulk discounts & roll back anytime.
T2 Pro Bulk Price Editor is a professional-grade app designed to help you edit product prices fast and accurate. For more info, click here.