In Oracle Apex, on button click, you want to open URL in a new tab. Here I am giving the example to perform this task using the Dynamic Action for a button.
Open URL in a New Tab on Button Click in Oracle Apex
Step-1: Create a button and set the properties highlighted in the below image:
Step-2: Now right click on the button you created and select Create Dynamic Action option. Then define the properties as shown in the below image:
You can use any URL here to open it in the new tab.