Is it applicaple to install windows on macbook pro 2021 without causing any issues with the macbook?

A free option to use UTM. UTM provides an easy to use graphical interface around the free open source QEMU software. If you use the ARM version of Windows, then performance should be Ok, but you will still have the same or perhaps even more restrictions/limitations than using the paid Parallels VM software.

Just remember that @JimmyCMPIT's suggestion for using a VM requires you to use the ARM version of Windows. There are restrictions with using the ARM version of Windows in a VM.....I know both Microsoft & Parallels both have some information on some of the limited features & modes of Windows ARM in a VM on an Apple Silicon M-series Mac.

However, UTM also allows you to run an Intel version of Windows since UTM is a machine emulator & virtualizer....meaning it is able to emulate a different system architecture such as an Intel CPU & system. The major downside to running an Intel based version of an OS with UTM is that performance will be much slower since it must emulate & translate everything using software.

Of course all of these options do require you to have a valid Windows license although I believe you can run Windows without one for testing purposes, but some Windows features will not be available without a license.

You’ll need to use a 3rd party application like VMware .

https://www.vmware.com/products/fusion.html

or paralells or some other virtualization software you can google and compare. Some are free, but most are not and you still need to buy windows (you can actually run windows for free legally, but some features ads blocked until you pay, there are some others ways to get windows 11 for free legally, you need to look those up yourself and at your own risk)

running windows on the Mac should do any harm to the Mac because it’s all sand-boxed , for instance; you can still get an infection on the windows instance but it’s limited to the windows virtualized instance.

as for the M1 it does not support running windows natively like the intel, so bootcamp is not an option. You will need to run windows on top of macOS but it will be in its own partition separate from the macOS install. The other features are dependent on the program you use. Additionally the ARM architecture was not designed to run windows so it may be a little sluggish. The Intel Macs were perfect to windows because windows uses that CPUs architecture perfectly, but that was in Microsoft’s wheelhouse.

Short term, you’re running a complex piece of software on top of your OS running another OS, if you’re not plugged in your computer your battery may need to do more than you might usually see. As to how much it really depends on what you’re doing. Long term it’s not going to effect the lifespan or health of the battery any more than normal use.

Glad you remembered that part of the OP's question. I forgot to address it as well by the time I clicked "Post".