The biggest blowout score at one point in the first half of an elimination game was 70-25 set by Cavs vs Heat last year
Tonight the Knicks have taken a 50 point lead in first half against the Atlanta hawks with a score of 72-22 , thus breaking the record set last year by the Cavs. Such is the consequences of the modern NBA
Edit : It’s 51 point as Knicks made it 76-25 later on in the half.
And for those wondering the all time record of the largest lead in first half at one point was 50 held by Mavericks Over Clippers December 27, 2020.
I think the Knicks have broken that record now