EDITED Apr-2021
If you go into the source code of an SVG file you can change the color fill by modifying the fill property.
<svg fill="#3F6078" height="24" viewBox="0 0 24 24" width="24" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
</svg>
Use your favorite text editor, open the SVG file and play around with it.
I figured out another way of changing the color from outside the SVG, and that is by importing the SVG content and removing the style rule where the fill is declared. And then controlling the fill from within my CSS style sheet.
<svg width="100%" height="100%" viewBox="0 0 167 134" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" xml:space="preserve" xmlns:serif="http://www.serif.com/" style="fill-rule:evenodd;clip-rule:evenodd;stroke-linejoin:round;stroke-miterlimit:2;"><g id="Pic_icon"><path id="Pic_icon1" serif:id="Pic_icon" d="M166.667,0l-166.667,0l0,133.333l166.667,0l-0,-133.333Zm-158.276,70.89l32.771,-33.148l48.814,49.375l31.519,-19.575l36.781,32.176l-0,-91.3l-149.885,0l-0,62.472Zm84.426,-36.017c11.25,0 20.384,9.164 20.384,20.451c0,11.287 -9.134,20.451 -20.384,20.451c-11.25,0 -20.384,-9.164 -20.384,-20.451c0,-11.287 9.134,-20.451 20.384,-20.451Z" <!-- remove this -> style="fill:#08e1ea;" -->/></g></svg>
Then inside my CSS file I go about:
svg{ fill: green; }
Now that You're removing the higher hierarchy fill declaration from the SVG the one outside takes control.
This works for me with no problem at all.