Hello

For the the first and last section (marked in the picture) - I have added the following css in custom css section. You should increase the font size as your need.

.sppb-addon-articles.article-border .intro-items .sppb-addon-article .sppb-addon-article-title {
    font-size: 15px;
}

For the center section (Tuje Lige) - I have added a csutom css class from the SP Page Builder front end, then added the follwoing css in custom css section:

.custom-font-tuje-lige .sppb-addon-article-title {
   font-size: 15px !important;
}