I’m not offended, I just don’t see the point in asking for help if you’re then going to ignore it.
If you want a ‘masses’ solution then you can google it. If you want personal experience, recommendations and advice then you can ask here. To do the latter and then still go ‘well sod it, I’ll do what I want anyway because Google’ seems rather silly to me. It’s like you’re not looking for advice, rather you’ve made up your mind before you started this thread and you’re just seeking validation for your decision.
You might well get away with it and it’ll be absolutely fine. You might well irreparably ruin your sofa. The entire question is based on speculation. An expert might be able to differentiate between different sofa manufacturers or cloth types or something but you haven’t provided that information so it’s guesswork. Your ‘sofa cover’ could be wool, hessian, PVC, polycotton, silk, leather, banana skins, human skin, tissue paper or butterflies’ wings for all anyone else knows. Is it safe to machine wash the cover when the washing instructions explicitly tell you not to? Who the hell knows.
But I’ll bet dollars to donuts that you do it anyway despite any advice anyone here gives to the contrary.