Without code
Modern Fields provide a block to show any value from your custom fields, so you don’t need code to display informations in your posts and templates.
Just insert the Field value block into your content.
Then, choose the value to display from:
- This post
- Options page
- Author
And finally, choose the field you want to display.
More options are available in the Pro version.
In your PHP templates
Alternatively, you can call the functions the_field() and get_field() to customize and display fields values in your templates.
PHP
Take a look at the dedicated documentation in the developer handbook.