How to make your playing sound more solemn?
One way is overdotting.
Overdotting is a practice in French Classical music to notate dotted rhythms regularly but perform them much sharper, something like with two dots. It's especially evident in French Overtures.
So instead of a dotted eighth note and a sixteenth note you would hear an eighth note with a double dot and a thirty-second note.
Composers who were inspired by the French style also used overdotting in their music (Bach, Handel, Bohm and others).
Plenty of overdotting is evident in Couperin's Mass for Convents.
See if you can spot similar instances of dotted rhythms in the Baroque music that you play.