signs my phone is cloned

Not sure what you saw. Your phone cannot be connected to remotely, so you don't need to worry if that was what you were thinking. Of course your web accounts, such as SnapChat and Twitter are easily changed and will be reflected on your device if your password is known. Changing your password on those account will solve that problem. If your Apple ID Password is known, your iCloud account can be modified and those changes will also be reflected on your device. Follow this link to change your Apple ID Password:

Change your Apple Account password - Apple Support

View if anyone is logged into your account by going to Settings > [name on top], and scroll to the bottom to see the devices logged into your Apple ID.

Safety Check can also be used to verify information about your account such as Trusted Phone numbers and view the information you are sharing with others.

How Safety Check on iPhone works to keep you safe - Apple Support

No matter what the signs are, your iPhone cannot possibly be cloned. You will have to find some other explanation.

Start here→How Safety Check on iPhone works to keep you safe