Will a 2700K bulb really make that much difference?

Yes. The shift from cool-white to warm-white changes the perceived temperature of the room more than any other $5 change. Try it in one lamp for a week and compare.

Should I buy a sectional for a small apartment?

Usually no. Sectionals work in small apartments only when they exactly match the room geometry. A regular two- or three-seat couch is more flexible and usually fits better.

What if my apartment is really small (under 400 square feet)?

All six hacks still apply. The leverage may be even higher, because every small friction is more visible in a smaller space.

Small-apartment living room hacks that don't cost much

Why small fixes beat big purchases in small rooms

Small rooms cannot absorb new furniture. Every new piece either replaces something existing or makes the room more crowded. The highest-leverage changes in a small apartment are usually the ones that do not require buying more furniture.

The six hacks below do not require new furniture. They cost a combined total of under $50 if you shop reasonably. They take about a Saturday afternoon to implement.

The six hacks

Replace one cool-white bulb with a 2700K warm-white bulb. The room feels intentional after dark instead of clinical. Cost: $5.
Add a wall sconce or move a floor lamp closer to the couch. Bring the light to where the body is. Cost: $0 (move existing) or up to $40 (cheap plug-in sconce).
Add a real woven basket within reach of the couch. Becomes the home for remotes, books, the daily pile. Cost: $25.
Add a silicone armrest tray with a cup well. Drinks have a home. The cushion stops absorbing accidents. Cost: $25.
Edit the rug situation. If two rugs overlap, remove the smaller one. If one rug is undersized, just accept it (do not buy a new one yet). Cost: $0.
Move the couch six inches in any direction. New sight lines, new walking paths, new feeling. Cost: $0.

Why these six are different from the usual advice

Most small-apartment advice tells you to buy ‘multifunctional furniture’ or invest in new pieces. That is expensive and usually wrong. The room already has the furniture it needs. The six fixes above make the existing furniture work better.

The bulb swap specifically

The single highest-leverage $5 change for any small apartment is replacing a cool-white bulb (4000K or above) with a warm-white bulb (2700K or below). Cool-white reads as clinical, like a kitchen or office. Warm-white reads as residential.

Most apartments come with cool-white bulbs because the landlord bought them in bulk. Swapping the ones in the living room takes five minutes and changes the room dramatically after sunset.

The armrest tray specifically

An armrest tray is the most overlooked small-apartment fix. The drink-on-armrest problem is the most common cushion-damage event in any apartment. A $25 silicone tray prevents months of accumulating damage.

The tray also removes the ‘where do I put the cup’ question, which is one of the small frictions that makes a small apartment feel cramped. The cup has a home. The mental space is freed.

What not to do

Do not buy a smaller couch. Whatever couch you have is the right size for the room (it fit when you moved in).
Do not buy ‘multifunctional’ furniture that does three jobs poorly. One good piece beats one clever piece.
Do not paint the walls white assuming it will make the room bigger. Color matters less than light temperature.
Do not buy a new rug to fix the small-rug problem. Accept the small rug or move it to a different room.

The Saturday plan

Hour one: bulb swap, basket purchase (or online order), armrest tray purchase. Hour two: move the lamps, add the basket, place the tray. Hour three: move the couch six inches and live with it for a day before deciding.

Total time: three hours. Total cost: under $50. Total change: substantial.

Small apartments respond to small fixes more than big ones. The six hacks above cost less than a single new throw pillow set and change the room more.