Do you have to thin them out when they get thick or can you just leave them?
Hi, some hosta plants keep growing in clumps and they can get as tight and large as you want them to be. Some of mine have grown out to the side with a separate clump, making the plant look uneven. That's when I dig it out and separate the side clump to plant elsewhere.
Hostas are probably the most resilient plants in my garden!
You could divide them but you don't necessarily have to. Your hosta(s) will get as large as the growing conditions will allow (and that can be pretty large, believe me!), at which point the plant becomes a perfect candidate for dividing and transplanting. If you decide to divide it, this article will walk you through how: https://www.gardeningknowhow.com/ornamental/foliage/hosta/transplanting-hostas.htm
And if you decide to leave it alone (and there is absolutely nothing wrong with that), here are some tips for continued care for your hosta: