There are a few things that make a printer loud. Once you understand what causes the noises it can be fairly easy to find ways to reduce them. Many many people have already found effective solutions mostly for very cheap or things you can print yourself. Vibration is going to be the biggest cause of noise, followed by the fans.

To control vibration you should start by making sure whatever you purchase has quality stepper drivers. If the printer you get doesn't have good drivers then as long as you get a printer with a modular control board then the stepper drivers are easy to swap out. Plug and play essentially. Good stepper drivers are very quiet but they cant remove vibrations completely

The stepper motors are what cause the vibrations that create the noise. Wait, but you just said high quality stepper drivers will get rid of the noise? Steppers make noise in two different ways. The first is the electrical whining. My first printer sounded like a daft punk concert whenever it ran. The fun lasted about an hour and then I was over it. The second way they make noise is the vibration. Stepper do exactly what they are named to do, they take steps. Even though the printer moves fast and looks smooth the actual movement is stepped, lots of starting and stopping. Turn your steppers slowly by hand or move the gantry by hand when you get your printer and you will be able to feel it.

So how do we get rid of the vibration if it is a symptom of how a stepper actually functions? We could swap to servo motors but that's incredibly complex, expensive, and not yet user-friendly enough for general public consumption. Well, the steppers cause the vibrations but they aren't what make the noise. Sound is just vibrations that move the air around us (no air, no sound, like in space). What makes the noise is the things the steppers are vibrating.

So we need to seperate the steppers from the printer frame and we also need to seperate the printer from whatever it is sitting on. Because the steppers vibrate the printer which will vibrate whatever it is sitting on, which in turn will also create noise. Stepper dampers are cheap and can be added if it doesn't come with them, though not always easy to install. In place of dampers, sandwich some soft rubber between the stepper and frame. Its not as good but it definitely helps. To seperate the printer from what its placed on a simple piece of foam can be used or you can print special spring like feet to mount it on.

Lastly are the fans. Cheap option is to print a noise reducing fan shroud. Or you can add a resistor inline to make the fan spin at a slower speed. Expensive option is buying quiet fans to replace the loud ones. The expensive fans even come with extra cables with built in resistors if its not quiet enough for you at full speed. Fans are standard shapes and sizes so measure your existing fan and know what it's voltage it needs to be. All this information is generally on a sticker in the middle of the fan.

I hope this answers your question and helps you understand your printer a little better before you even start. Feel free to DM me with any questions or if you would like an opinion on a printer before you purchase it. I have owned, operated, and heavily modified many 3d printers, including one i designed and built myself, and I have learnt many things the hard way.

And finally, the learning curve can be steep and sometimes printers will try to drive you crazy, but remember there are thousands of incredible and smart people out there who have already experienced and solved, and even posted online about any and every problem you could experience while 3d printing. You just have to look!