Show 4 lines of title text for videos on youtube homepage. See the following repo where this and other YouTube UI improvements is made into a UserStyle CSS script: https://github.com/acropup/acropup-UserStyle-CSS-Scripts#YouTube-UI-Refinements

youtube new homepage.css

/* Set height of video's text info */
div#details {
    height: 11rem;
}

ytd-rich-item-renderer.ytd-rich-grid-renderer {
    margin-bottom: 24px;
}

/* Move ellipsis menu to bottom left corner */
ytd-menu-renderer.ytd-rich-grid-video-renderer {
    margin-top: 9rem;
}

/* No vertical margin on video titles */
h3.ytd-rich-grid-video-renderer {
    margin: 0;
}
/* Let content overlap with ellipsis menu column */
#meta.ytd-rich-grid-video-renderer {
    padding-right: 0px;
}

/* Chanel name and view count, bottom right */
ytd-video-meta-block.grid.ytd-rich-grid-video-renderer {
    position: absolute;
    left: 42px;
    right: 0;
    bottom: 0;
}

/* Channel icon, bottom left */
a#avatar-link {
    position: absolute;
    bottom: 0px;
    left: 0px;
}

/* Show up to 4 lines of title text before truncating with ellipsis */
#video-title.yt-simple-endpoint.style-scope.ytd-rich-grid-video-renderer {
    font-size: 1.4rem;
    line-height: 1.8rem;
    max-height: 7rem;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: normal;
    -webkit-line-clamp: 4;
}