I use a shared hosting plan which allows me to add multiple websites with one account/purchase. I have one website in the same plan for my work, and one for personal works. I can see both of them in my file manager and they seem to be related (in administration part).
I want to know if any random person on the internet can use WHOIS or other tools to connect these two websites to each other.
There are some tools that show domains of the same owner (using their email) or show other domains of the same DNS. I personally see no reasonable way to do this.