Modern Vespa

I am buying a 2016 BV 350 with 300 miles on it, garage stored and in near perfect condition. Given it's a 3 year old bike I think the fluids should be changed (coolant, oil, brake fluid etc.), am I right? Also what about the 600 mile service coming up in 300 miles? Should I do it now or in 300 miles after brake in period is fully complete? Tires should be okay for another year or two (dry rot wise not tread wise), correct?
Also what issues should I look for or replace like coolant clamp, spark plug etc.
At any rate, your advice is much appreciated and if you think of anything I am not aware of please let me know.

Thanks in advance

Depends on how it is stored, but most manufacturers recommend replacing tires after 10 years based on time only.

If it was me I'd go for a hundred or so mile ride, and then change all the fluids, and consider that the break-in oil change.

Coolant hose clamps are known weakness, but I'd stop short of suggesting immediate change.

As to the spark plug, change that by miles not time.

Thank you for your reply. The bike is garage stored, I edited the original post.