I have bought a home in Sicily but I’m not a resident.

I have the opportunity to buy a 17 year old uk car in Sicily however it has no uk mot and has not been formally exported to Italy. It still has UK registration plates.

Can anyone advise what steps I would need to take to legally drive the car in Sicily. TIA

Do not touch it with a barge pole. Firstly as it has not had any MOT probably for years it is bound to be in a poor state mechanically. and may be unsafe to drive and cost a fortune to sort out. Many expats in Italy(and I have lived there) thought that it was a wizard wheeze not to register the vehicle in Italy and drove around picking up all sorts of tickets and not paying them .They then off loaded them to unsuspecting Brits who wanted to do the right thing but ended up with problems. Plus of course since Brexit re registering a car has become a bit of a time consuming process Personally in your position I would do car hire .
You might find this article useful and also there is an organisation called ACI which can help with vehicle bureaucracy

https://www.ilportaledellautomobilista.it/SDG/C1EN.html

It might have been worth having if it was old enough to be MoT exempt but I agree with the previous comment. Even if you were allowed to register a car in your name there it would be a nightmare process. I bought a car in Slovenia and registered it in Croatia. That added €1100 to a car that had cost €6000 and proved to be very nerve wracking. The irony is that Slovenia and Croatia were the same country 24 years ago. I do have an LDV Convoy which I brought in from UK but I can't see me ever getting it back on the road now it is not an EU vehicle.

You can no longer drive around on a foreign plated car for more than 6 months. So your only option here would be to get a visa and then residency, import the car, then pay for all the work needed to get it to satisfy Italian law. So I agree with the first comment - don't touch it with a barge pole.