How much data of a user allowed by law to get recorded by service providers?

Question

If someone from India has optical fiber connection internet for windows10 PC and mobile phone 4g network provider’s internet for android cell phone using 4g sim card, now sometimes he uses PC’s OFC internet in mobile and mobile’s 4g internet in PC using wifi hotspot and both PC and mobile phone’s internet/network service provider companies are different but constant, and he uses 1.1.1.1 and 1.0.0.1 as DNS server instead of ISP’s dns server for PC, and he saves all login credential on Edge browser on both PC and cell phone and two devices’ browsers are synced and he uses autofill during login in a website on Edge browser, then -

1)- Does/can ISP store all his browsing history ? also can/does ISP see/know what he’s doing inside a specific website like what he’s searching on google and which file he is storing in google drive, which files he is downloading, like can they know the stored/downloaded file’s name and content inside? Can/do they see His login credentials for a website? If they can then for how long do they keep the data stored before erasing completely? Does law allow them to do that and does law allow police to get those data from ISP and how much police can ask for?

2)- Does/can network service provider of a cell phone record all the voice calls/messages/whats app chats of a user? If so then for how long do they keep the data stored before erasing completely? Does law allow them to do that and does law allow police to get those data from ISP and how much police can ask for?

N.B. During the occurrence of all those above said events the user had no police case against him and Police was not trying to do anything at all against/about him and police did not even know his existence at all as he doesn’t have any criminal record in the past at all. But only days later of those events for the first time in his life police may start to try to acquire those above said datas which occurred in the past. N.B. Sorry for many questions at the same time, but those are so tightly related that I could not find a way to ask them separately.

Answer 1

Most of this is not technically possible

Almost all internet traffic nowadays uses SSL encryption. So all the traffic to and from websites is encrypted and cannot be read by your internet provider. Services such as WhatsApp and the like also use end-to-end encryption. So that means that even if the internet provider were to store that data, he cannot make any use of it. So unless your PC is infested by some malware, it's not possible for the ISP to know your passwords and login credentials. And storing all the traffic that is routed trough an ISP is just way beyond the capacity of any available storage system.

The only thing the ISP could save is information about the DNS requests, since they're not typically encrypted (as of now - Secure DNS is being implemented by many ISPs). From that information, it could be derived what sites you visited and how often, but not much more. Due to the large amount of data that even that would generate, it's not typically done.

I don't know the laws of India, but most countries do have a law that require them to store the IP address of your fiber connection for some time. Since the server owners do know your IP if you visited their website, they can ask the ISP for this information, if you abused their service. So for instance, if you start to constantly vandalize Wikipedia, your IP will be forwarded to the police, which in turn will ask your ISP who owned that IP during that time and then, in the worst case, an officer may ring at your door. But that is very rare. Even in this case, you are prosecuted because the owners of Wikipedia complained, not because your ISP knew what you where doing.