Given the year Schwarber has had in both Washington and Boston, I'd be very surprised to see him exercise his portion of he mutual option.
As for JD, I think it is a tough call. It all depends if he wants as much money as possible for 2022, in which case he stays, or he wants to try for a longer deal. At his age, every season reduces the changes of a multiyear contract. If he wants to gamble that the NL will adopt the DH, that would make this year his best chance.
Of course, if he does opi out, he will receive a QO (assuming they are still a thing) since Boston would be stupid not to offer him one (if he is turning down a $19.4mill season, why not have him turn down another ~$19mill one year offer on his way out the door?), which makes him less attractive to some teams. But then he might get one after 2022 as well, especially if he has a better season.
I don't think it's a simple as "will he get a raise on 2022?". Other factors do include the QO, the DH and his age if he wants a multiyear deal. Maybe he does not want to take the money for one season and risk having an off-season at a year older like Yoenis Cespedes or Edwin Encarnacion where no one came calling and he had to retire?