If you wish to add old price like this example:

and on the single property page:

To start please go to Offer Types:

1. Add new Offer type "Old price". Configure "Display before price" and set "show label on the property card"

then check "Add additional price field" and click "Add New Offer Type"

You will see new field on your backend property edition

To make it visible on the frontend submit property panel please visit MyHome Panel >