Locking files

No.

Notes ate locked individually and you need to use files like Word docs that yoh can lock with a password.

It will however be very difficult for someone without your passcode and Apple ID password to access files on your phone or in iCloud Drive

No, notice they have it only for Notes and Photos which are Apple apps. It is not on Files because the iPhone does not have a user manageable file management system. They could add it to Pages, or Numbers, or Keynote or similar Apple files is they wished to but with the team features of those apps it is not likely to happen.

You can suggest to Apple which other of their apps you would like to have this on by going here -> Feedback - iPhone - Apple

I'm not sure what your point is, are you saying that someone else besides Apple should choose how their iPhone works?

How many times (not counting Pegasus but that is for spies and journalists) has an iPhone been broken into or iCloud account been broken into without being given the passcode or password?

Answer Zero.

If it is likely that passcode or iCloud password could be known to family member you might want to use file passwords.

The only file I keep a password on is my word document holding all my passwords. Just in case I fall for a phishing attempt as I get older (I'm 70 now)

"...But I also keep getting a lot of pushback from “amateur experts”. Because they don’t like me question? ..."

We answered it, move on to somewhere else if you think you will get a more professional answer.

if you come here regularly you will find people being equally annoyed that Apple can't open their password locked Notes.

Impossible to please everyone.

Bchbum75 said, "...unless there's some innate design attribute that prevents it."

I already explained to you that there is a design attribute that prevents it. iOS does not provide for user file management and all apps are sandboxed. You would have to remove both of these design attributes to do what you want with the Files app, which is very unlike Notes or Photos. But Apple's security on iOS is fully built around sandboxing and no user accessible file management and I don't thing they are going to remove this to lock individual files in the Files app.

That is EXACTLY what I did tell you in my first response, that our Apple hosts chose to mark Recommended

ie You cannot lock the Files app but you can choose a file type that you can lock.

I did not limit the choice of files to Word, that was merely one suggestion based on my personal experience.

If pdfs can be locked then great.

Because Apple chose to do so.