I have an iphone 8 - 64k and have spacing issues and I don't always get the period to show after hitting the space key twice. Also the enter key doesn't always move if I want to space down.

Hi Willypeg,

Thank you for using Apple Support Communities. It sounds like you’re having intermittent issues with your keyboard. I’d be happy to help.

First, I suggest making sure that the “.” Shortcut is enabled under Settings > General > Keyboard, and that the other settings are adjusted to your preference as well.

If the issue remains, I suggest making sure that your iOS is up-to-date. You can find instructions for doing so here:
Update your iPhone, iPad, or iPod touch - Apple Support

Lastly, you can try restarting your iPhone as a next step if you're already using the latest version of iOS.
Restart your iPhone, iPad, or iPod touch - Apple Support

If the issue remains, feel free to reply with more details.

Cheers.