How to change all collapse icons?

Help
1

I want to change all collapse icons to

image

And I got icon svg code

<svg xmlns="http://www.w3.org/2000/svg" x="0px" y="0px" width="24" height="24" viewBox="0 0 172 172" style=" fill:#000000;"><g fill="none" fill-rule="nonzero" stroke="none" stroke-width="1" stroke-linecap="butt" stroke-linejoin="miter" stroke-miterlimit="10" stroke-dasharray="" stroke-dashoffset="0" font-family="none" font-weight="none" font-size="none" text-anchor="none" style="mix-blend-mode: normal"><path d="M0,172v-172h172v172z" fill="none"></path><g id="original-icon" fill="#ffffff"><path d="M71.66667,42.49609l-10.75,10.75l32.7539,32.75391l-32.7539,32.7539l10.75,10.75l43.5039,-43.5039z"></path></g></g></svg>

and URL-encoder for SVG

But how change it ?

Thank you so much !

2

I changed folding mark from one unicode character to another here: More visually distinct folded/unfolded marks - #3 by malecjan

I do not now CSS enough to say if it is also possible to replace by SVG icon. I would be interested in solution if you succeed.