Got it!
What about: grid-template-rows: 80px 1fr 1fr;
and a fixed height for p (with overflow scroll)?

... (if the min-height is removed) only the first 3 lines should be displayed

Hi!
Have you trided
p {
box-sizing: border-box;
min-height: 6.5rem;
display: -webkit-box;
-webkit-box-orient: vertical;
-webkit-line-clamp: 3;
overflow: scroll;
padding-bottom: .5rem
}