Can a blocked contact still call me or text me?

I have an iPhone and was wondering if my blocked contacts can still call me or text me

No… That's why it is called "BLOCKED"

Depending on how they are Blocked, when they call they will go to voice mail. They can still send you email, but not SMS. If you are using an I'm type app like Instagram or WhatsApp that is APP to APP, unless blocked in those apps, they still can send to those apps.

Of course if they call you from a different number, or are using a SPOOFING app that tricks Caller ID by allowing them to show any made up number or random number, to your Caller ID, they can still call or text you sing that. But most people are too lazy, to go to that extreme, most get the hint when you stop replying to their text or all their calls go straight to your voice mail and you never get back to them. The truly dense get restraining orders placed on them.