Is this for remote access?

If your iPhone is managed/administered by an Organisation / Corporate/enterprise and if they have installed Device Management Profile then these links will help you.

If your iPhone is individually owned and you have installed an app which prompted you to install a profile then these may help you.

Otherwise, these will be for academic purposes only

Get started with a supervised iPhone, iPad, or iPod touch - Apple ...

Install a configuration profile on your iPhone or iPad - Apple Support

Is this your corporate iPhone? Do you have any profile installed by your corporate / organisation/enterprise / School Management then please contact the system administrator of your corporate / organisation/enterprise / School Management.

If you have installed any profile on your own --> Install or remove configuration profiles on iPhone - Apple ...

If you want to turn on SSL trust for that certificate, go to Settings > General > About > Certificate Trust Settings. Under "Enable full trust for root certificates," turn on trust for the certificate. Apple recommends deploying certificates via Apple Configurator or Mobile Device Management (MDM).

Trust manually installed certificate profiles in iOS and iPadOS ...

If you feel an unauthorized person/app is remotely accessing, controlling, or monitoring your device, then that is possible only if you have done one or more of the following Don'ts...

1. Don't hand over an iPhone to kids or to a stranger without Enabling Guided Access
2. Don't share Apple IDs
3. Don't Jailbreak
4. Don't share sensitive information pertaining to your device
5. Don't give in to Phishing
6. Don't plug in your device for charging your device in Airports, Public Transport, or public places, and trust the device. Beware of Juice Jacking. (Especially in India)
7. Don't leave your iPhone unlocked and unattended in public places like offices, schools, malls, etc.

If one of the above is true then quickly change the Apple ID Password and Return iPhone settings to their defaults.

I use iCloud+ on my iPhone 12 Pro with Family Sharing between 5 family members. All are using the shared iCloud Storage.

I also use Dual SIM:- Physical SIM Google FI (USA) and eSIM Airtel (India)

Settings > Mobile Data >

• Mobile Data Switching > Disabled
• WiFi Assist > Enabled
• iCloud Drive > Enabled

Settings > Mobile Data > System Services: I do not see RemoteICloudQuotaUI 

It would be better if you can please re-post with a screenshot, in order to understand the phenomenon better. Images/pictures speak louder than words. 

Please understand this is a public forum: While attaching a Screenshot, do not provide any personal credentials, such as IP address, Card detail, email id, apple id, IMEI number, Serial Number, Phone number, Order ID, if you are sharing a map ensure your location is not identifiable, etc.

"RemoteicloudQuotaUI" has nothing to do with Family Sharing?

The screenshot you have pasted is for the system services pertaining to your Cellular Data.