I have to make lavel, some uneven slope area to make a patio. So can I use wood chips to make that area lavel? After filling that area with wood chips, can I put gravel and sand before laying patio stone?

Wood chips will eventually rot and settle further and then the patio stones will be worse off than if you do it right in the first place.

You can pack dirt first,then stone compacted,then sand,then stone.

The uneven area,is some of it high verses the level you are attempting to level?If not,get fill dirt,not topsoil,and compact it with a tamper,a 2X6,anything to make it stiff.

You'll be much happier in the long run if you do it right in the first place.