You can add drapery panels to the door to add texture and warmth to the room

The mirror over the FP is not large enough and would be better in a bronze frame finish

A floor lamp in the corner is a better solution that a chandelier

Large panel art over the sectional is required.

There is no way to determine the color of the sectional from this photo so here's a multi panel canvas in blue.

You need to have a come to Jesus discussion about toys in this room. No one wants to end the day in this clutter.

Paintings are certainly needed, but I would first change the color of the walls to something a little darker. Perhaps from the taupe palette or something similar.

I would split your room into two. Shift your sectional down to the front window and move the tv to that end of the room. Find a lower tv stand and either hang the tv or just place it on the stand but make sure it's secure since you have little ones. Set the other end of the room up as a kid area with toy storage and maybe a games table. Your exercise bike can stay back at that end.

What room leads off from the wall by the window? A sketch of the floor plan with measurements, windows sliders, exits detailed will help determine a layout to accommodate the bike, TV, seating, kids stuff. The last item to tackle will be art, since furnishings may move.

IMO have aspace designated for toys so maybe where the chair and table are a nice cabinet where all the toys can go when entertaining . I see 2 kids both seem old enough to have most of their toys in their rooms . As for the rest the mirror gone and replaced by a piece of art . The cabinet for the toys and the cabinet under the TV the same . The sectional moved so at least some seats are facing the TV the tread mill needs a new home Or as mentioned split the space to have TV and toys Sorry I do not think kids need every toy they own in my LR ever

Some visual

Like Beverly floor lamp suggestion.

I am including a link to a great source for inexpensive canvas art, they even have extra long options. With such a large room, you would benefit from very large or oversized canvas prints, no frame art to cozy up the feel. with lots of color, especially being such a young family.

https://www.greatbigcanvas.com/view/turn-it-on,2519691/

Your TV could be lowered a bit for optimal viewing. Do you need the cabinet below?

I would move it to the far end of the living room and allocate that area to childrens play area.

I would also replace the mirror over the fireplace with a framed art piece, for a calmer look. try it over that small table next to the chair and move the whole seating/table to the other side of the room with the sofa so you can see the TV/Fireplace.

if your feeling real ambitious, I would paint the chimney and fireplace surround a deep rich color, so it's a feature in the room.

a floor lamp would throw better light than the swag fixture. like a tree lamp with three heads.

If you post a floor plan showing all dimensions, doors, windows, fireplace we might come up with a better layout for fit your needs. The chair and console look stuck in the corner and not part of the conversation area, and perhaps storage solutions can be suggested for all the toys.