I didn't  see what Liferay version you're using, but on 7.2 and 7.3 you can do this with the Custom Filter widget.

See Filtering Search Results for more details, and let us know if you run into any issues.

Great, then you can use the Cusomt Filter widget. It's a bit hard to see but there's a hyperlink to the docs in my last post. Here it is again, less disguised:

https://learn.liferay.com/dxp/7.x/en/using-search/search-pages-and-widgets/search-results/filtering-search-results.html

Ahh shoot, you are trying to sort not filter. I shou;dn't have replied before having any coffee :(

So sorry to send you down the wrong path, let me look into it a bit more.

When I use the sort Portlet, the URL result is something like ...&sort=createDate%2B, I need to create something like that using the custom Filter i guess

Is there a reason you're not using the Sort Portlet?

Yeah, I see what you mean. I expected that if we put the created option at the top of the sort configuration, it would be applied on page load. But it's not. I'm going to check two things:

1. Is it expected that the first option in the sort widget should be applied by default?
2. Is there another way to enforce the default sort order in the results widget?

I've asked these questions internally, and so far, we think you've hit a bug in the sort portlet. The first option configured in the Sort Portlet (Relevance OOTB) should probably be applied on page load, so switching the order to use created as the first option should be all you need to do. However, as you and I have both observed, it's not working as expected.

I've filed a ticket here: https://issues.liferay.com/browse/LPS-123103