I've reached my $2.5K tax that I expect to owe for this year. On new W-4 21' how do I adjust so I get $0 more taken out? Adding $ to 4(c) line hasn't helped, 2 small?

I first tried $1000 on the 4(c) line, then $4000, has not made an impact to more going into my pocket.  Need more than the 'basic' info I'm finding online.