The 2024 Dungeon Master's Guide contains a 'toolbox'. The DM's Toolbox is the third chapter in the book, presented as an alphabetical miscellany of varied things to help you prep or run a game.
Each entry is 1-2 pages long and includes things like creating monsters, fear and mental stress, chases, firearms and explosives, and traps. For example, it goes in depth into chases, with details about wilderness or urban chases.
Much of the topics were already in the 2014 DMG--albeit organized differently. Some new topics include character death, and more detailed look at alignment--and how actions determine alignment and not vice versa.
Also included is a big table of 'dungeon quirks'--why, then, and by whom was it built? Examples include made by giants (with everything being larger scale), built on top of a cloud, and so on.
There's plenty more stuff--environments, a settlement tracker (Chris Perkins and James Wyatt roll up a random settlement in the video), hazards, mob rules, marks of prestige (rewards like deeds, medals, or titles).
