Even changed the List/ Library advance Settings still it's not reflecting back. would like to change the classic view to modern view. For IE: Clear the Cache in below screenshot highlighted icon on the Network tab and refresh the page again. For Chrome : Open developer tools(F12) in the browser. Just click F12 function key. Click on the application tab, expand the cookies section and select the SharePoint online site which you currently working on. Delete the one with the name ‘spinu’ that has the value 0 Refresh the browser and that’s it!! you are now moved to the modern view.
You can create Max of 500 records in post request call if you include more than records better to call multiple requests this way you can achieve