Can an expression acknowledge the Comp's name?

I have to create many variations of a comp. There is a specific labeling system I have to use and I'm wondering if I can set up a if-then situation to adjust parameters based on what I name the comp.

so for example i have a comp name:

PRIMEHD_P2_L2_TSS

and I want the expression to look for the number after that "L" and adjust a slider number (BAR LENGTH SLIDER) to match that digit. in this case "2"

possible? i ask because i know very little about how to format a label to be read, especially pin-pointing a specific position in that label.

thanks

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