Probably not if all the light is coming from the sconces.

Assuming each sconce takes a 60W incandescent bulb which produces ~ 800 - 900 lumens, you have between 5600 to 6300 lumens. That does not take into consideration shading due to the sconce or directionality - whether the light is directed up or down.

If you want ~ 20 lumens per sq ft, 19 * 21 * 20 = 7980 lumens.

The ceiling height could be problematic for recessed lights as most installations are for ceiling heights

There will be a light with the ceiling fan. Great room ceiling is about 18!feet. Is there a standard height for sconces?
Davidtay, what type of lighting do you recommend for 2 story great rooms if recessed lightings may be problematic? Thanks for the feedback!

The placement height depends on the size and style of the sconce.
The ceiling fan will need a pretty long "neck" and shadow patterns may result.
Several possibilities
1. Cove lighting - you can imagine it as being a continuous sconce along the wall.
2. Use LR6-DR1000 or similar recessed can.
3. Chandelier/ hanging fixture
4. A combination of light sources such as cove lighting + Chandelier/ hanging fixture.