I've recently tried making americano from my Breville Dual boiler machine. I've tried making it with a 1:2 and 1:3 ratio to the hot water from the machine and a double shoot espresso (16g in, 36g out).
It tastes nothing like the an americano from a restaurant. It takes quite bitter whereas the cafe ones are much more blended in (not sure how to describe it).
I tried searching for receipes online, it's not very specific, they just say add hot water to your espresso.
What is the trick to make a cafe like americano at home?

There is a cafe in Sydney I have visited that makes wonderful long blacks (aka Americanos). The barista told me he can't duplicate the coffee at home using the same beans from the cafe. He said his equipment at home isn't identical. But he can still make a good cup.

The first thing is to pull a really tasty shot of espresso. That's the hardest part.

You also need good tasting water, preferably at the right temperature. Although if you use boiling water it just means you have to wait for the cup to cool down before drinking.

Then there's the question of the amount of water to add. It's really personal preference, the strength of the beverage, and depends to a certain extent on the dose size and type of coffee. FWIW, when I pull a shot from 18g of beans I top it up with water to roughly 4.5 fluid ounces, the volume of a small Cappuccino cup. That means my Americano is at a strength of about 2.5%, give or take.

Finally there is debate about whether to pour water into the shot or pull the shot into the water. There is some difference in presentation (appearance of the crema) but I don't think it makes any real difference to the taste.

As John stated above, the first thing to do is make a good espresso shot. After you have managed to do that, then there are really only 2 variables. Amount of water and temperature of water.

I moved from a Breville Barista Express to a Lelit Bianca recently. One of the first things I learned with my new machine was not to bother with using the water from the hot water wand. Since it is superheated in the boiler, it comes out of the wand at 100C. This was too hot to drink and also seemed to give my drink an unpleasant taste. Now I use the hot water from the grouphead and run it through the portafilter, so that I don't get grinds from the shower screen in my cup. Since this should be very close to the temperature of my espresso shot, it doesn't impact the taste. I could use a kettle with adjustable temp, however, right now I don't have the counter space to add another appliance.

The amount of water will depend on your preference. Although I usually have a set amount for each different bean, I will vary it slightly if I think a previous drink I made was a bit too watery.

Use fresh, not boiler, water about 2x shot volume.
Heat to ≈170°F/75°C in the cup
Pull shot into hot water.
Enjoy

If the shot is bitter, blame the espresso

Cafes don't use hot water from the machine. Most have a separate hot water boiler set around 200 F for the purpose of tea brewing and Americanos. Use a tea kettle. As for the water adding it's highly varied though most shops I have worked in pour shots to cup and add water after. Many want room for cream so adding water before the shots can lead to over topping.

Personally I like my Americanos very strong. I add equal parts water to espresso though sometimes add a bit more.

Kaffee Bitte wrote:... adding water before the shots can lead to over topping.

Not if you measure...

Once you have nailed a well extracted espresso shot and are using clean, quality water, another variable to consider - your coffee versus the restaurants' coffee.

Are you using similar roast levels and flavor profiles?

Maybe you could sort of calibrate by visiting a local cafe, tasting their Americano, and buying that exact espresso blend to make at home?