Softer?
There are two 'sorts' of recoil. Actual recoil and perceived recoil.
As RC said, physics is the law of the universe and cannot be avoided. The combined mass of projectile and propellent gases, and spacers, wads, sabots and anything else - all lumped under the catch-all title of 'ejecta' - times the velocity of the ejecta, then divided by the mass of the firearm is the amount of recoil force involved.
So a lighter bullet, less powder, no 'packing' and a heavier firearm all work to reduce what it commonly known as 'free recoil'.
However, there is a 'perception' factor. A narrow back strap and grip which puts the recoil force into a smaller area causes more discomfort in the hand - which SEEMS like greater recoil. Sharp edges do the same when those sharp edges bear against the hand. Rubber grips tend to cushion the recoil thrust and make recoil seem less.
The over all velocity of the ejecta makes a difference in perception. Typically a shotgun or large bore but slower round (.45-70 Govt comes to mind) stretches out the recoil pulse over a longer period; the recoil is not as 'abrupt' and the perception is the recoil is lighter.
A long gun with a greater angle between barrel and shoulder stock tends to rise more. If the long gun smacks one in the face on recoil, this is uncomfortable and SEEMS like greater recoil.
One other factor which is quite subtle is the powder burn rate. Faster powders accelerate the ejecta more quickly and the recoil pulse is quicker and feels more abrupt. Slower powders accelerate the ejecta more slowly and - subtly - tends to lengthen the recoil period. Which makes for less 'perceived' recoil. (This is predicated on maintaining the same or reasonably same velocity.)
One other trick I have used to reduce felt recoil - with handguns - is to load a heavier bullet at a much slower velocity. The slower velocity tends to stretch the impulse over a longer period - subtly again - and recoil seems softer.
With factory ammo, one has little control over much of this. However, with 'cushy' grips, the velocity of the projectile is not influenced. By the same token, a set of 'heavy' grips will soften the recoil impulse. But that makes it heavier to carry, if that's important.
No. There really is no free lunch.
