If it looks messy or if it's smashing another plant, you would want to stake it up. To do this, you can buy some half moon stakes at a good garden center and just prop those stems back up. If your plant is big, you'll need 3 and they can run $7.00-8.00 each. It won't look good, because the flower
stems have bent, but it will work and can be used from year to year for various plants like Peonies.
Or you can get a stout stake (not a little flimsy bamboo stake, but something substantial) and run it down beside the crown of the plant. One by one, gently get the stems to a more upright position and tie them using a figure eight -- one 1/2 loop around the plant and one 1/2 loop around the stake.
This is time consuming, and also, the flowers
will be facing the wrong direction, but they might straighten up. The other peoblem with this is the length of twine you use will be very visible and none too attractive.
Alternately, you could cut the stems down so you have the crown of the plant, with some short stems, saving as many leaves on the stems as possible, by cutting down the flowers
with the longest stems possible. You'll still have to stake the plant if it throws more stems. To do it this way, you can use the flimsy bamboo stakes (the ones they sell in 3 or 4 foot lengths in a pack of 10) and make a sort of ring, or corset. Or you could tie each stem to a bamboo stake.
I don't know why some Echinaceas do this and some don't. I drive by houses that have huge beds of this stuff maybe 10 feet x 20 feet and it's obvious they don't garden at all and the flowers
are standing straight up. Come to my house, where I slave away on my garden daily and I have a huge 'Magnus' coneflower that sprawled like yours. Is it too much love? (Water & fert) or Not enough sun? Or just the habit of the plant? I don't know,, but would love to hear from anybody else who has this problem!
You could also do nothing and leave it alone. :)