Yes but it is a lot more complex than that.
The umpire has to firstly determine the following.

Did the ball hit the pads first outside the line of stumps on the offside, if so did the batsman offer a stroke. If he did not and in the opinion of the umpire the ball would have hit the wicket.

Did the ball hit the pads first outside the line of stumps on the legside, then the batsman is not out.

If the batsman is right back on his stumps, it makes the job a lot easier, becuase you can clearly judge if the ball would have hit the stumps.
The way that the wicket has been behaving the way it has, then the batsman would need to be on the backfoot, for me to be able to give them out.

If the batsman is on the front foot, that is a lot more difficult to judge.

If somebody is bowling at 90mph, it is extremely diffcult to make positive decisions. As so often happens, a batsman is given out LBW, when in actual fact it was a no ball, because the bowlers foot has gone over the pop in crease and the umpire hasn't picked it up.
To pick that up and then have time to judge where the ball pitched and where the ball would end up, is so difficult.

Slow Mo makes it so easy to make a decision, when you are sitting snugly in your armchair.

It is my firm belief that all LBW appeals should be referred to the 3rd umpire, with feedback to the umpire at the wicket, who then makes the decision.

Any doubt, not out.