Hello,

Please add this code to the Theme Settings > Custom CSS > Global:

body .woocommerce-checkout-review-order-table tfoot .order-total th {
    font-size: 14px;
}
body .wcf-embed-checkout-form table.shop_table tfoot tr:last-child .woocommerce-Price-amount {
    font-size: 14px;
}
body .wc_payment_method label{
	font-size: 24px;
}
body .woocommerce-checkout #payment div.payment_box p{
	font-size: 12px;
}
body .wcf-embed-checkout-form #payment .woocommerce-privacy-policy-text p {
	font-size: 12px;
}
body .wcf-embed-checkout-form .woocommerce .woocommerce-terms-and-conditions-wrapper .woocommerce-terms-and-conditions-checkbox-text {
	font-size: 12px;
}

Set the font-sizes as per your needs.

Best Regards