You need to thin your seedlings. It's part of gardening. You are hurting the seedlings by letting them grow on top of each other -- they won't thrive.

What is the mature size of the plant supposed to be?

Hi Jojo thank you for responding. I’m not sure it’s been several plants. I did start on and planted some the way it is supposed to be. It just was sad after getting them to germinate them to have to let them go.

im new to gardening so I was hoping that could thrive and still do well even though there were several plants on one.

If you carefully dig up the clump you can separate the seedlings and replant them separately. You do not have to sacrifice any. But you do need to thin them out. If you need further help you need to tell us where you are located and what you have sown.