A quick video on replacing a handle on a UPVC window, very esy to do, 2 screws, one hidden under a cap, that other under the handle.
Check the screw length of the new screws, are the same, don't use too long ones which may damage to window! Enjoy
Here is an Amazon link to a good Yale handle I have used, this has two extra spindles (the square bar) at different lengths. The standard one, in the handle as it comes, is 40mm long and works in my windows. The other two are 15mm and 30mm and may be useful if you have thinner windows or are unsure which handle to get (this is an affiliate link where I earn a huge commission! lol)
https://amzn.to/4dsrUOq