How to use site_url() in Elementor

I have created a website in wordpress, which is currently running as sub domain of a company. This website contains large number of pdf documents, which are belongs to different categories. The pdf's are placed in a page called downloads, which is created using elementor plugin. I have included a button to download every pdf. The link of button which is like http://domain_name/subdomain/wp-content/uploads/2019/01/pdf_name.pdf. I want to purchase a domain for my site. And How to change the link address to http://my_domain/wp-content/uploads/2019/01/pdf_name.pdf. Whether we can represent the site home address like base_url() in codeignitor?. I tried ?php echo home_url()? and ?php echo site_url()?. But it only added to the current url address as echo%20site_url(). How to change it using the site address.