Is the Magic Keyboard for iPad Pro 11 inch (M5) compatible with a iPad Pro 11 inch 4rd generation?
iPad Pro, iPadOS 26
no,
go to their keyboard page iPad Keyboards - Apple
scroll down and choose your ipad in the list, it will then display the keyboard(s)
which support your ipad
Presumably you refer to the Magic Keyboard for iPad Pro 11" - this being the model with the integrated Trackpad:
If so, yes - the current iteration of the Magic Keyboard for iPad Pro 11" M5 is fully compatible with the iPad Pro 11" M4.
All physical dimensions - and the location of the associated Smart Connector - are identical for these models of iPad Pro.
More information about the current range of keyboards for the iPad Pro - and compatibility - can be found here:
Does Magic Keyboard for iPad Pro 11 inch (M5) for 4rd gen
