Comprised Account

If other people have access to your iPhone or other Apple device, change the device passcode and never share it with others.

Change your Passcode -> Use a passcode with your iPhone, iPad, or iPod touch - Apple Support

Change your Apple ID password -> Change your Apple ID password - Apple Support (IE)

• Create a strong password for your Apple ID, It is best if your password consists of eight or more characters and include upper and lowercase letters, and at least one number. You can also add extra characters and punctuation marks to make your password even stronger. 
• Never provide your password, passcode, security questions, verification codes, recovery key or any other account security details to anyone else. Apple will never ask you for this information.

Then see this Apple article: What to do after you change your Apple ID or password

What to do after you change your Apple ID or password - Apple Support

(if you haven't already done this) Two-factor authentication for Apple ID -> Two-factor authentication for Apple ID - Apple Support

To keep your Apple ID account secure, see the following Apple articles: 

If you think your Apple ID has been compromised

If you think your Apple ID has been compromised - Apple Support

See who has access to your device or accounts

See who has access to your iPhone or iPad – Apple Support (UK)

Delete suspicious content from your devices

Delete suspicious content from your devices – Apple Support (UK)

Check your Apple ID device list to see where you're signed in

Check your Apple ID device list to find where you're signed in - Apple Support

• if you see devices that don't belong to you, delete from your account.

Personal Safety User Guide

Personal Safety User Guide – Apple Support (UK)

Manage and use your Apple ID

Manage and use your Apple ID – Apple Support (UK)

Never jailbroken your iPhone.

Same here. No one has account access. My physical sim doesn’t even show as an available sim and I’ve never added any esim. My internet login was cloned. Every single electronic device I have that is Bluetooth capable has been altered in some way in its settings in a way that I cannot change them. About 9 months of phone calls, reading, anxiety, messed up accounts, no account access to some things. Frustrated and angry, I feel every inch of my privacy has been invaded.