Is there a way to edit a "native" Google Analytics 4 dimension?

I want to edit the Landing page dimension in GA4 to only show the first two parts of the page path (for example "/first/second/third/fourth", I only want to show "/first/second") instead of the whole path + query string - is there a way to edit this dimension so that it's displayed differently in GA4 interface?

Or, is there a way that I can use the url parameter from the Landing page dimension to create another dimension (to avoid changing the original Landing page dimension) with shortened url?

The reason why I want to do this is that the page path dimension is very high in cardinality on my website and I want to group the landing pages so that I have less cardinality in the Landing page dimension.

Yes, you can override the default landing page dimension and yes, you can put the url in a different dimension.

There are two native dimensions, dl (document location) and dp (document page). You can override them like so:

Using page_location and page_page. The inconsistencies in dimension names in the protocol and in the GTM UI are due to how rushed all this ga4 business is. We normally just drop the query params from the page dimension to reduce cardinality. But you may want to cut off more than that.

You still can do that if you use gtag.js directly to track things. By setting those dimensions with the gtag configure call.

Using similar approach, but different names for event properties, you can set up custom properties for this tracking.

If you're setting custom properties here though, you would need to make corresponding custom dimensions in GA4 UI for them to become available.