which Tex-command can draw a bracket overlap a line?

documentclass{article}
usepackage{chemfig}
begin{document}
    chemfig{-[@{op,.75}]CH2-CH(-[-90]cl)-[@{cl,0.25}]}
    polymerdelim[height = 5pt, depth = 25pt, open xshift = -10pt, indice = !!n]{op}{cl}
    
end{document}

EDIT To make bond lines thick and color

documentclass{article}
usepackage{chemfig}
begin{document}
    chemfig[
            bond style={line width= 1pt ,blue}
            ] 
            {-[@{op,.75},0.75]CH_2-CH(-[-90,0.75]Cl)-[@{cl,0.25},0.75]}
    polymerdelim[height = 5pt, depth = 25pt, open xshift = -10pt, indice = !!n]{op}{cl}
    
end{document}

EDIT2 -- To make the delimiter mov closer to the atom removed the open xshift=10pt