Yes, but only for items up to £20 in value and 100 gms in weight, in some categories, which ebay have unhelpfully failed to give details.
All they say is when listing, if the item qualifies you will be offered opportunity to use your own postage.
Read for yourself, the bit about opting out is right at the end. Why if it is so Simple does it need so much explanation.
https://www.ebay.co.uk/help/selling/posting-items/setting-postage-options/simple-delivery?id=5575&st...
