Pokemon Sword and Shield will have some free events coming up from time to time. One that we should definitely look forward to is a Gigantamax Buterfree encounter in Max Raid Battles. As the official website says, the event will be live until "early January 2020".

You'll initiate this event upon accessing the Wild Area. This is an MMO-like environment and you'll see hordes of players running around, catching all the distinct Pokemon species and doing group content together (of course, that includes raids as well).

The event itself is really fun and you should definitely check it out. You have more than enough time to do so.