Depends on the make and model. Windows 7 has generic / built in drivers for most parts, but there is no guarantee that it will for the laptop that you end up buying. You can go to the manufactures website if they've specifically wrote a driver for that laptop for Windows 7 too, but like I said -- It all depends.
There isn't a easy way to downgrade back to Windows 7 from 10, especially if the laptop is brand new. If you buy your laptop from a retail store, they may offer a service to do it for you for a fee. Or find a friend that is tech sauvy to do the setup and installation for you.
I do NOT suggest you attempt this yourself unless you are comfortable with the steps. However, like all of the operating systems before it, It will eventually be discontinued. Windows 10 isn't that bad once you get used to it --but really, that's with everything.
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