You can actually see what happens. Assign your mod, and in the casr of offense, pay attention to physical and special damage numbers. They should increase by the value of the mod.
Read the ability. They typically state deals physical damage or deals special damage.
The damage done non-crit, number you see on the screen, is
(physical/special damage * ability multiplier) *(1-armor/resistance)
There is a damage variance of typically 5%
Ability mtiplier can be found on swgoh.gg site
Example
Rey has ability multipler of 2.210 on her basic so adding 100 offense will add 221 damage before armor to her basic attack
5's has ability multipler of 1.232 on his basic so +100 offense will add 123.2 damage before armor to his basic attack.
The ability of the character will define that. I'll use QGJ as an example. His basic attack causes physical damage, Harmonious Assault causes special damage, and humbling Blow causes special damage. The abilities that cause physical damage are based off the "Physical damage" stat, whereas the abilites that causes special damage is based off "special damage" stat.
Another example is Wedge. He has two abilities - one basic and one special, yet they both cause physical damage, not special.
Some characters inflict special damage on basic attacks, such as Emperor Palpatine.
I couldn't tell you the difference between the two - it just seems entirely random which is which.
Replies
The damage done non-crit, number you see on the screen, is
(physical/special damage * ability multiplier) *(1-armor/resistance)
There is a damage variance of typically 5%
Ability mtiplier can be found on swgoh.gg site
Example
Rey has ability multipler of 2.210 on her basic so adding 100 offense will add 221 damage before armor to her basic attack
5's has ability multipler of 1.232 on his basic so +100 offense will add 123.2 damage before armor to his basic attack.
Another example is Wedge. He has two abilities - one basic and one special, yet they both cause physical damage, not special.
Some characters inflict special damage on basic attacks, such as Emperor Palpatine.
I couldn't tell you the difference between the two - it just seems entirely random which is which.
But the mods apply the bonus to both.