If all you did was open a link nothing bad happened. It is not possible to install malware on a phone from a website. If the site tries to download something iOS would intercept it and ask you if you really wanted to do that. And even if you did approve it the worst that would happen is it would install an annoying calendar or profile, which you could easily delete.
If you think you might have approved it and you want to check go to Settings/General and scroll to the bottom. Look just below VPN. If you seen an entry for “Profiles” open it, and if you see anything suspicious just tap it and delete it. Then go to Settings/Passwords & Accounts and scroll down to Subscribed Calendars. Again, if you see any that you don’t recognize tap on it and delete it.