Would a mattress topper make my bed feel less firm

A topper will absolutely soften it up. Just don't get a super soft one or you'll bottom out. I'd look at a medium-firm latex topper, maybe 2 inches.

You'll sink like a stone if you get memory foam. Ask me how I know.

How do you know?

Because my 250-lb self spent a month in a memory foam crater before I gave up. Latex or a dense polyfoam is The way to go for bigger folks. Memory foam just remembers all my regrets.

I'm 260 and added a 3-inch soft latex topper to a firm innerspring. It made a huge difference for my shoulders. Still supportive underneath. Just don't expect it to fix a mattress that's already sagging.

Toppers are a band-aid. If the mattress is too firm for you, it's the wrong mattress. But cheap band-aid vs new bed? I get it.

Two years is long enough to know. Try a topper before you drop a grand on a new bed. Worst case you're out a couple hundred.

Careful with the thick toppers though. I put a 4-inch one on my bed and it felt like sleeping in quicksand. My spine was not thrilled.

How thick was it? 4 inches seems like a lot. I was thinking 2 inches max for a heavy sleeper.

Yeah 2 inches is probably smarter. I'm 220 and the 4-inch was overkill. Learned my lesson.

Also check the density. A soft topper with low density will compress down to nothing under 280 lbs. You want something that's actually rated for higher weights. Latex holds up well.

Or just sleep on the floor. Zero firmness complaints. Your hips might disagree though.

Good luck. And seriously, avoid the memory foam. We can't have another crater incident.