Yes, absolutely. The single product uses the default WooCommerce font size:
.woocommerce div.product p.price {
font-size: 1.25em;
}simply change 1.25em to any size you wish.
can use % or px also. e.g. font-size: 1.25em; is the same as font-size: 125%; (125% of the body font size)
font-size: 20px; if you prefer to use pixel size