Not all chip leaders are equal. Some play very loose and aggressively and like to run over the table with frequent raises and large postflop bets. Some like to sit on their chip lead and not play a hand unless it's premium.
If he likes to sit tight, then I don't worry about him unless he's in a hand with me. I'll play as usual. It's when a chip leader is loose and aggressive that it compromises my usual strategy, and I have to look for opportunities to trap and/or resteal.
I recently played in an MTT against a LAG with a huge chip lead who was basically playing 90+% of
hands and calling every raise, even all ins. He was catching very well, plus he was sitting directly to my left, which complicated the problem. I had to play a lot tighter than usual, knowing I could not play back at him without a real hand and without risking all my chips, because he would often call you down or put you all in.
I picked my spots and was able to knock out other players and double through some others on all-in shoves. Eventually he stopped catching and was knocked out short of the money, and we were able to play normally and make steal attempts once again.