m=1.01
Plot[{Sin[x],m x},{x,-.2,.2},PlotStyle->{RGBColor[0,0,1],RGBColor[1,0,0]}]

Plot[Sin[x]/x,{x,-Pi,Pi},PlotRange->{-.2,1.2},PlotStyle->RGBColor[1,0,0]]

Plot[Sin[x]/x,{x,-.1,.1},PlotRange->{.99,1.01},PlotStyle->RGBColor[1,0,0]]

Animate[{Plot[{Sin[x],m x},{x,-2,2},PlotRange->{-1.1,1.1}, PlotStyle->{RGBColor[0,0,0],RGBColor[1,0,0]}],m},{m,-2,2}]
m

m

Animate[m,{m,-2,2}, AppearanceElements->{m}]

Plot[(Cos[x]-1)/x,{x,-10,10}]

Plot[{Cos[x],1},{x,-2,2},PlotStyle->{RGBColor[0,0,0],RGBColor[1,0,0]}]