IsDlg=1 in Modern SharePoint – SharePoint Stack Exchange

Yes, evidently there is a functional equivalent for Modern SharePoint Pages, Lists & Libraries.
By appending the following query string to the URL of a Modern Page, List or Library, the Page Header and Nav Bar are removed:

?env=Embedded

See Table Below


Also, there is another query string you can use to ensure that the Suite Bar is rendered, but it only works with Modern SharePoint Pages – not Lists or Libraries.
If used on Lists or Libraries in Office 365, this query string will automatically redirect the user to the Microsoft Lists Application render of the List or Library requested:

?env=WebViewList

Before ?env=Embedded in URL After ?env=Embedded in URL
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