If you look up a definition of lexical scope, you'll typically see something like this (from https://en.wikipedia.org/wiki/Scope_(computer_science)#Lexic... but others are similar).

"With lexical scope, a name always refers to its (more or less) local lexical environment. This is a property of the program text..."

So as local lexical environment isa property of the program text, lexical scope is explicit in the language's syntax.