Where can I buy alt layer?

Could you please elaborate on where I might be able to acquire an alt layer? I've been hearing a lot about the potential of altcoins and the role that alt layers play in the cryptocurrency ecosystem, but I'm not entirely sure where to start. Is there a specific exchange or platform that caters specifically to alt layers? Are there any considerations I should make before making a purchase, such as the reputation of the exchange or the volatility of the altcoin itself? Any guidance you could provide would be greatly appreciated.