Атрибут svg:viewBox
Масштабирование и центровка средствами вьюбокса
HTML
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 317.855 317.855" width="50" height="50" style="border: solid 1px grey;"><g fill="gray"><path d="M158.93 317.855c-1.03 0-2.06-.16-3.052-.477-33.344-10.68-61.732-31.168-84.377-60.89C53.674 233.085 39.4 203.96 29.076 169.92 11.66 112.507 11.46 61.36 11.46 59.21c0-5.15 3.913-9.46 9.04-9.955.772-.075 78.438-8.048 132.553-47.347 3.504-2.546 8.25-2.543 11.753 0 54.1 39.3 131.776 47.272 132.554 47.348 5.123.5 9.034 4.807 9.034 9.953 0 2.148-.2 53.296-17.613 110.712-10.323 34.04-24.597 63.165-42.425 86.566-22.644 29.723-51.032 50.21-84.376 60.89-.993.318-2.022.477-3.05.477zM31.747 67.982c.83 16.784 4.062 55.438 16.604 96.59 21.405 70.228 58.6 114.87 110.576 132.747 52.096-17.917 89.335-62.712 110.713-133.203 12.458-41.074 15.654-79.434 16.473-96.134-22.404-3.27-80.438-14.332-127.186-45.785-46.752 31.45-104.774 42.515-127.18 45.784z"/><path d="M153.582 207.625c-2.372 0-4.68-.844-6.5-2.4L110.92 174.3c-4.197-3.59-4.69-9.902-1.1-14.1 3.587-4.198 9.9-4.692 14.098-1.1l28.124 24.05 55.743-73.118c3.348-4.392 9.622-5.24 14.015-1.89 4.393 3.348 5.238 9.623 1.89 14.015l-62.155 81.53c-1.667 2.187-4.16 3.59-6.895 3.882-.353.036-.706.055-1.058.055z"/></g></svg>
<p>Уменьшим</p>
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 500 500" width="50" height="50" style="border: solid 1px grey;"><g fill="gray"><path d="M158.93 317.855c-1.03 0-2.06-.16-3.052-.477-33.344-10.68-61.732-31.168-84.377-60.89C53.674 233.085 39.4 203.96 29.076 169.92 11.66 112.507 11.46 61.36 11.46 59.21c0-5.15 3.913-9.46 9.04-9.955.772-.075 78.438-8.048 132.553-47.347 3.504-2.546 8.25-2.543 11.753 0 54.1 39.3 131.776 47.272 132.554 47.348 5.123.5 9.034 4.807 9.034 9.953 0 2.148-.2 53.296-17.613 110.712-10.323 34.04-24.597 63.165-42.425 86.566-22.644 29.723-51.032 50.21-84.376 60.89-.993.318-2.022.477-3.05.477zM31.747 67.982c.83 16.784 4.062 55.438 16.604 96.59 21.405 70.228 58.6 114.87 110.576 132.747 52.096-17.917 89.335-62.712 110.713-133.203 12.458-41.074...