How I do get access to windows explorer in the new view of document library
"Open with Explorer" in a SharePoint Online document library Classic Mode
- In the SharePoint Online document library, click the Library tab on the ribbon, and then click the
Open with Explorericon in the
Connect & Export group.
"Open with Explorer" in a SharePoint Online document library Modern Mode
- If you don’t have the Library tab, and you're using the new look and navigation experience for document libraries, click the
view menu(for example, All Documents) in the upper-right corner, and then click
View in File Explorer.
For more information check How to use the "Open with Explorer" command to troubleshoot issues in SharePoint Online
In order to "Open in File Explorer" you need to be using IE 10 or 11. I don't believe this works in Chrome, Firefox, or Edge.
Assuming you are using IE 10 or 11 the option can be found by clicking the All Documents drop-down from the top right side of the page and you will see View in File Explorer below
Edit: here is a screenshot