My left frond disc brake drags more than the right. I have changed calipers, pads, pins, and hoses, and the left brake drags more than the right side. Is there any trick to reduce this? Thanks.

What kind of master cylinder do you have?
Drum brake master cylinders have a residual pressure valve that can cause drag.

You might have some residual pressure from the booster/master if the piston/rod air gap is not adequate?, have you checked this?.... your air gap should be between .020 to .060

Try opening the bleeder on the LF and see if the drag goes away. If it does, hit the pedal a few times and see if it returns.

If if does, Open the bleeder on the opposite side and recheck the drag. if it is still there you have a restriction somewhere on the L side hydraulics, a sticking caliper piston, mounting pins, misalignment etc.
If it is not, then the problem is somewhere else in the hydraulics like the MC pushrod, Porp valve etc.
keep us posted

I had a similar problem and I replaced the stamped steel 2 finger retractor springs on the 2 pins with small coil springs from Ace hardware. Solved my problem

How thick are your rotors? The further the piston moves out of the caliper the more resistant it will be to return.