There is default sort in XC5 - https://demostore.x-cart.com/admin/admin.php?target=general_settings
- "Default order to sort products within a category" and "Default order to sort products within a search result"
However keep in mind XC5 uses lots of cached and cookies values for various elements so it is possible once you visit site as customer and change sorting order any sub-sequential visit (or page load) will use that same order - as it is now set as preferred order for you. XC4 will reset the order with every session.
Moving from XC4 to XC5 will result in lost of some features, others have been moved to modules (some paid), but will also get some new features.
There's always a trade off. How you can justify it? XC4 is dead, has been for the last 4-5 years. It is unfortunate but it's the reality. For good or bad XC5 is the cart in active development now.