I have a 2018 model X with FSD. It's current HW is 2.5.
I heard some people got the message from Tesla for HW3 upgrade, but I didn't get any message yet.
Do I need to make an appointment for the upgrade?
I think you can set up an appointment using the Service option in the Tesla app. Many months ago, before I had the upgrade done on my Model 3, there was an option there for scheduling an upgrade. I'm not sure it's still there currently for owners with HW 2.5, but you can always choose "Other" and type in your request.
We designed and engineered our Full Self-Driving (FSD) Computer from the ground up to rapidly process neural networks — the foundation for how we train and develop Autopilot. While no Tesla cars are fully autonomous today and require active driver supervision, the FSD Computer is capable of...
That support page suggests "'Schedule Service’ > ‘Accessories' > ‘Upgrades & Installations’ and add ‘FSD Computer Upgrade' in the description"