How do I use Apple Mail, without losing privacy?

Privacy Questions
1

As I’ve read so far, it seems Apple Mail isn’t really a very bad option compared to ProtonMail. I’ve also read that the security on Apple Mail can be further improved. Something called S/MME (I think ?).

So I’ve decided to use Apple Mail as the new email client. What are the settings I can change to improve my privacy?

Also, am I right in thinking Apple mail is pretty secure? I’m talking about the one that ends with @icloud.com .

3

I read somewhere that something called S/MMe can be integrated into your apple email and it makes it extra secure.

Any clue about this?

5

S/MIME is different from PGP and requires a certificate. It is only ever used in business (not much anymore) and there’s almost 100% certainty nobody you know uses it or has set it up.

It’s used even less than PGP, and you can’t use it with Proton Mail.