Answers for "make svg bigger css"

css svg width 100%

<svg height="100%" width="100%" viewBox="0 0 100 100"  preserveAspectRatio="none">
   <path d="M0 0 L100 0 L50 100 Z" />
</svg>

svg auto size

// Javascript to run after document load
var svg = document.getElementsByTagName("svg")[0];
var bbox = svg.getBBox();
svg.setAttribute("width", bbox.width + "px");
svg.setAttribute("height", bbox.height + "px");
svg.setAttribute("viewBox", `${bbox.x} ${bbox.y} ${bbox.width} ${bbox.height}`);

increase svg thickness

OLD:
<div style="width: 100px; height:100px;">
  <svg viewBox="0 0 100 100">
    <path d="M 50,0 L 60,10 L 20,50 L 60,90 L 50,100 L 0,50 Z" class="arrow" transform="translate(85,100) rotate(180)"></path>
  </svg>
</div>
<br>
NEW:
<div style="width: 100px; height:100px;">
  <svg viewBox="-10 -10 120 120">
    <path d="M 50,0 L 60,10 L 20,50 L 60,90 L 50,100 L 0,50 Z" class="arrow" transform="translate(85,100) rotate(180)" stroke="black" stroke-width="10"></path>
  </svg>
</div>
 Run code snippet