Hello,

To change the title you need to use the loco translate plugin.

You can also watch the video in our detailed documentation in the following link: https://www.youtube.com/watch?v=D3NsDdMzsls

To change font size Please try adding the following Custom CSS in the Global Custom CSS area under Theme Settings >> Custom CSS.

.related-products .title {
    text-align: center;
    font-size: 32px;
}

Best Regards