Hello ... to get the ball rolling:

What is the wall color, and can they be repainted or do you want to keep them as is?

Can you change the rug?

Is the sectional staying for sure?

What is the current window treatment, and do you need privacy?

What is on the other side of the room?

What budget for changes are you working with?

These will help with suggestions. :)

My first thought is a lighter or more colorful rug, with either a lighter ottoman or coffee table ... sheer panels on window (or ivory linen, etc) ... end tables with lamps on each end of sectional, or a multi-arm arc lamp over sectional ... art on walls (colors don’t matter, just what you like looking at) ... pretty throw pillows and throws.