Mark Felton has a great YT channel. Same for Drachinifel, History Guy, Yarnhub, Greg’s Airplanes, Armoured Carriers, The Museum of Flight, The Tank Museum (Bovington), Military Aviation History, The History Underground, and Simple History, just to name a few.
I can easily blow an entire lunch break on these without realizing it.
Metatron is also a great history channel for primarily Roman and Medieval topics.