What are the risks having visited a counterfeit or phishing web page on iOS? I received from a regular colleague a sharing e-mail in iOS Outlook, and clicked the link. It opened a web page asking for my credentials, which I did not enter because I recognized the page as counterfeit.

Is there any way to tell whether simply visiting the page resulted in a drive-by injection?
Is there anything I should do to ensure my device is as clean as it was before clicking the link?
Is there a reason to uninstall and reinstall Outlook on the phone?

Technical Details

iOS 14.0.1 ;
Microsoft Outlook for iOS 4.57.2 ;
iPhone Xs Max
It's very unlikely that you were infected with anything or that anything negative happened overall if you did not enter your credentials. My reasoning for this is as follows:

It asked for your credentials, which indicates the goal was phishing not infecting your devices
Drive-by infections are not impossible, but they're also not easy. Unless you're a high profile target it's unlikely you would ever interact with one.

I don't believe there is any reason to be concerned based on how you described this.