change the size of excerpts

Hi there,
I’m having a question about the excerpts on the home page of my blog: https://www.passion2create.nl

Before I installed the Duena theme, I used to make my own excerpt, and it was a little bit like this:

introduction text introduction text introduction text introduction text introduction text introduction text introduction text introduction text introduction text introduction text introduction text introduction text introduction text introduction text introduction text introduction text introduction text

<nice looking picture>

read more tag

And after the read more tag, people could read the rest of the blogs.
But the Duena theme makes the excerpt looks different. It’s only 2 or 3 lines of text and then READ MORE-> But I don’t want this new look. I just want my old version back, with the possibility to chose my own read more tag wherever I want to place it. Is there any way I can fix this back to normal, maybe? I am using Child theme by the way.