In the right setup/situation, the LRS can play plenty loud (perhaps not super loud/live rock concert levels).
I have no issues playing a wide variety of music and movies at spirited levels (I’ve never actually measured the db level; maybe I’ll do that). My LRS are about 6.5ft from the main listening position, crossed over at 80hz to a very capable sub, and powered with a beefy amp (Parasound Classic 5250, 385 wpc/4 ohms/45 peak amps). Of course, if running the LRS full range, sitting further away/larger room, that will certainly place more limits on how loud they will play at the listening position.
Certainly, the lower the volume one plays, the less power that’s required. If underpowered though for the circumstances, Maggies tend to sound a bit lifeless. Personally, I would err towards more power than I need rather than risk being underpowered.