Page build in HTML and wanted to load into JS view in SAPUI5 application.

The most commonly used way of doing this is to embed the HTML page as an iframe. Here is the example.

new sap.ui.core.HTML({
   preferDOM: true,
   content: "<iframe src=''></iframe>"

It can also be loaded using AJAX call or display using sap.ui.core.HTML, but it will depend upon your HTML page.