New Mac has some sorta parental controls and won't let me visit certain websites/apps

User wrote " This is an home computer so we don't have an computer admin. ". Please verify in System Preferences >> Users & Groups >> then check how many account s are listed and what Account is an Admin. Account. If your account is Not Listed as Admin. suggest taking to the Admin. of this computer about your issue

Can speak to the website issue.

Are there any AntiVirus, Disk Cleaner, Optimizers, Un-installers, etc installed which should be removed as per Developers Instructions. They are useless, unneeded, cause havoc and interfere with the normal operation of the OS and may even Corrupt the OS requiring a Reinstallation. The Built-in Security of Big Sur is all that is required.

There should be a little Apple icon in the top left corner of your display. Tap that Apple icon. At the top of the drop down menu, you should see a line that says this: About This Mac. Tap that About link and you should open a window showing the name and version of your operating system. You should also see 2 buttons, System Report... and Software Update... along with 6 tabs. That system window should open on the Overview tab.

Can you open that system window? What version of macOS is on your Mac? By the way...

1. What kind of Mac are you administering?
2. Have you done an initial (standard for most people) Recovery Reinstall?

Recovery boot: Shut Down. Restart holding down ⌘ and R keys at the same time (⌘-R). Select option Reinstall MacOS.

If this is a new-to-you Mac, and you took over existing accounts and logins, you’ll want to re-install macOS, as otherwise you’ll be tangled with previous settings and previous Apple ID ownership, and other related messes.

When you first powered up this Mac, did you see what is described in the following link?

Set up your iMac - Apple Support