"Grid (Flex)" is a render type of Dynamic Posts (old version) that shows a grid system based on the flex display property. Flex elements can be used to distribute space proportionally, as they widen or narrow, to avoid overlap or excess.
You can enable:
Use the years above the block.
You can choose:
Enable or disable Flex;
If Flex is enabled, you can enable Flex Grow. With Flex Grow enabled, the last elements have the ability to flex themselves to grow if necessary.
Query of 6 posts, with Flex enabled
Example (Flex Grow)
Query of 5 posts, with Flex Grow enabled. The elements in the second row flex themselves to grow.