When entering a corner (let's say without power), the two wheels will not need to rotate at the same speed : the outside wheel is having more distance to do than the inside one.
When having an open differential, it is exactly behaving as needed, so compare to an lsd you are having less understeer : the lsd will tend to make the wheels to rotate at a less different speed, making the turn-in less easy. But it will have the advantage to help a bit on the braking zone, and what you may call understeer may be translated in more stability (this why there is a coast parameter).
When on power, the car (FWD) should not by magic turn more/have less understeer. But in the current physics (someone will correct me if I am saying bs), I think there is a common issue with tyre grip that make at least for FWD to rotate a bit too much when accelerating with a high level of power for the lsd (this is why you will see the setups to go quick in FWD using very stiff front antiroll bar and a locked differential.
On a more logic configuration, you will reduce the values of LSD to reduce the understeer, adjust the antiroll bar to give more or less grip (stiffen the rear antiroll bar to give more grip to the front for example), you can play with the dampers, the toe, the camber, the springs, caster, etc ... The best is to read (I found this :
https://en.lfsmanual.net/wiki/Basic_Setup_Guide ) over internet to find out what are the purpose of all the settings available.