When you run DISM tool, Windows creates its log and saves it on your disk. This article shows how to view DISM log files on Windows 11/10.

I'm looking for a log file viewer that can handle simultaneously viewing multiple arbitrarily wide log files. This is like 'less -S' or toggle-truncate-lines in emacs, where it *does not* do this ...

Open Windows Services by opening Run (Win + R), type “services.msc”, and click OK. Now, you need to look for the Event Log (or Windows Event Log) Service, right-click on it, ans select Properties.

The Operational event logs (you have to dig down further in the Event Viewer to see these) contain a lot of the detail that the old USERENV.LOG file would provide.