Start with the topic guide.
Variables and types, arrays, functions, strings, classes and objects, interfaces and traits, namespaces and autoloading, Composer, errors and exceptions, handling requests, sessions and cookies, PDO and databases, type declarations, and PHP-FPM.
This is a learning outline. A complete worked tutorial has not been published for this topic yet.
Concept scope
PHP Language Fundamentals: 14 short lessons, one for each concept. Variables and types, arrays, functions, strings, classes and objects, interfaces and traits, namespaces and autoloading, Composer, errors and exceptions, handling requests, sessions and cookies, PDO and databases, type declarations, and PHP-FPM.