In a certain code language, 'HWET' is coded as '205238' and 'RBKX' is coded as '2411218'. How will 'ICPZ' be coded in that language?

Let's look at the standard alphabetical positional values (A=1,B=2,…,Z=26) for the given letters:
Case 1: HWET

Positional values: H=8,W=23,E=5,T=20

Let's list these positional numbers in reversed order (from last letter to first letter): 20,5,23,8→’205238’
This matches the code exactly.

Case 2: RBKX

Positional values: R=18,B=2,K=11,X=24

Listing them in reversed order: 24,11,2,18→’2411218’
This also matches perfectly.

Applying to ICPZ:

Positional values: I=9,C=3,P=16,Z=26

Reversing the order of positions: 26,16,3,9→’261639’