Add this code to the Custom CSS field on the Style tab of your Instagram Feed widget’s settings:
.eapps-instagram-feed-posts-item-text {
max-height: 260px !important
}
.eapps-instagram-feed-posts-item-text {
line-height:15px!important;
}
.eapps-instagram-feed-posts-item-text {
font-size: 13px;
}