Placeholder Color Change in Bootstrap

.form-control::placeholder { /* Chrome, Firefox, Opera, Safari 10.1+ */
            color: red;
            opacity: 1; /* Firefox */
}

.form-control:-ms-input-placeholder { /* Internet Explorer 10-11 */
            color: red;
}

.form-control::-ms-input-placeholder { /* Microsoft Edge */
            color: red;
 }

The following is the reference link. https://www.w3schools.com/howto/howto_css_placeholder.asp