Design with Elementor and code the rest?

Do you guys know if it is possible to design a website using Elementor or any other editor and then coding the rest using my custom PHP code?

I tried to use a theme downloaded from the internet and when I started editing with Elementor the design does not reflect on theme files, hence I cannot add code to the website.

I am asking this as I think designing the website will take a lot of time for that purpose I want to use a theme from the internet and edit using Elementor then add my custom code…