ὅσῳ ἂν πλείους ὦσι, τοσούτῳ μείζω καὶ ἐκπεπληγμένον μᾶλλον τὸν φόβον κέκτηνται.
This ἐκπεπληγμένον μᾶλλον τὸν φόβον is probably a rhet. fig., in which a characteristic of the possessor is transferred to the thing possessed.
Yes, it’s similar to English “panicked fear,” a transferred epithet or ὑπαλλαγή.