but if possible write any code php in blank app
Not sure what you are asking? If it is “can you write PHP in a blank app” - then the answer is yes. You write the PHP code for the app in the only event it has - “onExecute”.
As adz sais, I think you have to be more precise about what you want. Blank app is like an empty PHP file, but you can use sc macros and [global vars] will be translated to PHP as in any SC app.