How to load a WordPress entry page once

What is it you want to do?
Showing the page that is requested is what the web is all about. Did you want to show different content at that address, sometimes? Why? How would you know when to show which content? What is the goal?

I think you’re looking for a sort of “welcome” page which only first time visitors see. Detecting a repeat visitor isn’t always that reliable and can involve privacy issues in some jurisdictions. You can set a cookie to detect repeat visitors, but visitors could remove it, use a different browser or different device and your site wouldn’t know. More reliable would be to show different content to those logged in, but then people have to log in.

You could set the repeat visitor page as your home page and if the user does not appear to be a repeat visitor, redirect them to the “welcome” page. Instead of a redirect, you could have the front page template be capable of either output and act according to whether a repeat visitor is detected or not.

Yes I want to create a welcome page that only loads the first time for each visitor.

I found a way to do it using the Elementor Pro plugin by creating a full screen pop-up. The controls built into the Elementor popups allow for session control and a wide range of other options so problem solved. And the best bit about this method is I can use the elementor editor to design the welcome page.