few days ago I had a conversation with other user about some procedure, one of them is taking a long turn (270 degrees), as I remember when you take a turn bigger then 180 degrees the aircraft will take the short turn, the person I was taking to said that in modern airliners MCP will take the direction of the turn no mater how many degrees  you take so I took it to a test' I took the NGXU and the NGX, took heading of 360 and start turning the heading right, I set the heading to 270 and when passing 180 the aircraft didn't took the shortest turn to 270, it keep turning to 270 from right bank, It make 270 turn.

So I made the same test with the 757 and when reaching 180 (out of 270) the aircraft took the shortest turn and from turning right it turn left.
I made the same test with the 767 and the same result.

now I'm not a pilot and I want to know if it something that haven't been coded into the MCP behavior or due to the 757/767 been older it's the real way that the MCP behave?

I also attach Illustration of this situation

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757/767 works differently than the 737.

The 737 ONLY has a heading select button, so it works like you described, direction of the knob but only if HDG SEL is already engaged.
On the 747/757/767/777, HDG SEL is always use the shortest turn. (Maybe the 747 and 777 have something new but that's how I'm aware of it).