With Justified Gallery Type you can show your ACF Gallery like a justified image grid.
This effect creates an elegant image gallery with different sizes of images, where all the images in the same row have the same height. This gallery type tries to show images without modifying their aspect ratios and without cropping them. If limited by the maximum row size, it can sometimes crop the image to fill the grid.
You can choose:
images space, the space between images,
if justify, align left/center/right ,
hide the last row.