Looking for some guidance on open concept room and 3.1.2 vs 5.1

Open concept living room

Hey everyone!

I did some digging around in the sub, and found out the basics about 3.1.2 vs 5.1, even if I never personally heard it, dunno if they have showrooms like this in brazil or a 30-day trial.

The Samsung Q800 catched my attention, but here is some more info:

• I have a moderately big living room/dining/kitchen, its open concept, roughly twice the lenght of whats in the image;
• I have a 55" Samsung TV, I don't remember the code, do remember it being QLED and having an earc port. I'll get the code when I get home later if its important.
• The Q800 is pretty much the upper ceiling of my budget, if it really is the best for its price, I might as well get it. I'm open to suggestions but I cant go any higher currently, as its already pretty expensive here (3300 to 3500 brazilian reais);
• Bass is important to me, not earth-shattering, but feeling it would be a game-changer, specially for someone who never had a home theater system;
• I could be open to buying rear speakers later, monitoring its prices and finding a good sale eventually, but its not mandatory for now (and I think my budget for now wouldnt even allow it);
• I have a vinyl speaker and a ps5 I would love to use with, even if movies are more important.

That's mostly it, I highly thank everyone who takes their time to read and help me with this, even a little. I'm open to suggestions, maybe a newbie like me should start smaller with a 3.1 system, I dont know. Feel free to share video/text material!

Thanks again, everyone!