I used to consider it as a method too, a long time ago. Turns out I was just fooled by mainstream media. Although, it's still possible to die from it. Suicide by cutting your wrists is pretty complicated, you have to overcome your survival instincts, and it gets hellishly painful when you reach the fat tissue.
In this scenario, it's much harder to push past your instincts compared to, say, the jumping method. With jumping, all you do is step off, gravity does the rest. But with cutting, you have to apply force yourself, and maybe even do it multiple times if the first cut isn't deep enough. You'll see rivers of blood leaking out, and your survival instinct will be screaming at you inside your head. You might even just "shut down" and not be able to move your hand at all.
Honestly, I think to actually go through with it, you'd have to be in a severe state of psychosis. As for the pain (and just to be clear, I'm NOT a medical professional, so don't take this as actual medical advice), I think you could use a local anesthetic to numb the area. I looked into them before but forgot the names, you can research that yourself.
If you try it though, you'd need to know how to do a subcutaneous injection properly. And if you're going deeper (which is most likely), you'd probably need another shot afterward, otherwise, you'll feel raw pain. Maybe, before even using an anesthetic, you could hold your forearm in ice water to dull the pain more, though that might also slow blood flow.
To silence your survival instinct (not that you're actually getting rid of it, that's impossible), you can take benzos. I think you need to take them, like, an hour beforehand? I've never taken any kind of psychoactive drugs myself, so I can't say for sure. Please, if you're seriously considering this method, or feel like it's your only option right now, do thorough research to make it less painful (physically and mentally) and to ensure it's effective. Wish you peace and I hope everything gets better❤