format external ssd as Windows 11

no,

you will need to use a virtual machine like parallels or vmware or virtualbox to run the arm version of windows 11 on an arm based mac computer

Options for using Windows 11 with Mac® computers with Apple® M1®, M2™, and M3™ chips - Microsoft Support

older macs had intel cpus so one could use bootcamp to run windows directly on the hardware, but with apple moving to arm cpus and microsoft not selling their arm windows 11 version to end users that put an end to bootcamp

you can also get ms office for mac computers, though I think ms pref people rent their office 365

not, really no

the new cpu from apple used the ARM cpu architecture where the version of

windows microsoft sells rely on the intel/amd x86/x64 cpu architecture

the fact that you install it on an external hd does not make any change to the fact that the 0's and 1's in the binary sequense on the x86 windows on the external hd would be gibberish for the arm cpu in your mac

only way to make it work would be an x86 emulator for apple arm platform which could perform fast enough, maybe you can find an emulator which would run windows 95, would not run office 2019 of cause

if you want to know more

What apple say:

Apple: It's Really Up to Microsoft to Make Windows Work on M1-Based Macs | Tom's Hardware (tomshardware.com)