Hello i own a legacy 3.0 automatic 2007 and need to know if it.s possible to switch engine to a smaller one ?

Like the 2.0 or 2.5 automatic.

Bolt on or do i need alot more job?

Where i live in sweden there is not so easy to find a 3.0 in good condition.

I think you will run into computer problems and definitely working problems. The 3.0 is wires for 6 injectors so the harness will not work with the smaller motor

You will need a complete donor vehicle. It would probably be cheaper to import a used engine, or just sell the car and find another one.