Lots of my seeds are sown in seed-trays (called "flats" in the USA , I believe. In the UK, a flat is what Americans call an apartment...), or in pots. When the plants grow to a size that makes it practical to transplant them (usually when they have two proper leaves), I move the best ones into separate pots. Recently I have done this with my Endives. I have two varieties of Endives, "De Meaux" and "Caillard".
At this stage they don't look much different, although the De Meaux ones are mostly a fair bit larger, even though both were sown on the same day.
I will grow the Endives in these 3 and 4-inch pots for another two or three weeks, after which I will plant them in their final growing positions in one of the raised beds.
I have been doing the same with Purple Sprouting Broccoli too:
I have potted-up four each of "Early Purple" and "Red Spear".
Meanwhile the Leek seedlings are coming along nicely. These "Apollo" ones are not far off the so-called "pencil thickness" stage, at which they are best planted out in their final positions.
Whereas the "Winter Giant" ones which I sowed later are still very small. This is probably just as well, since at this moment I don't have much available space for them.
