I was in a similar situation to you OP and opted for an ELCS.
Ultimately shoulder dystocia is hard to predict, but larger baby (esp large head / broad body) is a risk factor. Even if you are higher risk they likelihood is it won’t happen.
Most babies are born following shoulder dystocia are fine - the biggest risk is nerve damage to the arm which usually resolves in days/months but can sometimes be life-long. Occasionally babies suffer oxygen deprivation which can result in brain damage or, very rarely, death.
Because of the risk of oxygen deprivation when it happens it is an emergency and action will be taken to ensure the baby is out as fast possible which can result in a traumatic delivery (physically and mentally).
For me, the decision was that, although the chances will still low, having been warned of the possibility, if the worst had happened I would never have forgiven myself and I was happy to sacrifice the hope of a ‘good’ birth for what felt like the greater certainty of an ELCS.
I’d had a forceps delivery with my first (so history of a less than smooth delivery) and my 2nd was predicted to be 12lb +. In the even he was ‘only’ 10lb 7oz but had the biggest head and widest shoulders you have ever seen on a baby so I feel I made the right choice!
I still feel a little sad about not getting a natural birth but my recovery from the ELCS was good (not going to lie the first two days I was in agony but after that my recovery was better than it was following the forceps delivery), and I can’t even really see my C-section scar now.
If you definitely want to be scared into an ELCS watch the last episode of ‘This Is Going to Hurt’, otherwise don’t even consider watching it until you’ve safely given birth. But there’s a more realistic example of a safe shoulder dystocia deliver on One Born Every Minute, there’s a clip on YouTube if you google it.