Thanks for contacting us and choosing our product!
Now in our theme have 5 Testimonial style and all is slideshow.
In this case you can choose one of style you want to display as multiple rows and customize template display via child theme follow this topic:
Example: you need edit file: wp-content/plugins/haru-pangja-core/templates/posttypes/testimonial/carousel.php (the file name depend on style of testimonial you set at backend)
You can remove slide settings on line 44: https://prnt.sc/tnbymi
And add custom CSS code for get grid style.
Hope this help!