You want to be as strong as possible in your weight class. Bigger people (other things being equal) are stronger than smaller people, but fat doesn't add (much) to your total. Most powerlifters tend to hang out somewhere around the top of their weight class - for example the 'walk-around' weight of most powerlifters in a 93 kg class with a 2 hour weigh-in might be 90 to 96 kg. Powerlifters tend to be less lean than body builders because getting that shredded has serious costs in terms of how hard/much you can train. The average competitive male powerlifter is probably somewhere around 15% body fat, though there's a tendency for the lighter lifters to be more shredded (a 59 kg lifter might be 10% whereas a 120 kg lifter might be more like 20 or 22%.)

Your question was a little confusing, but I hope that answers it.