Sometimes fate blesses or curses a combatant, causing the novice to hit and the veteran to miss.
Sage Advice
Spell attacks can score critical hits, just like any other attack.
Source: Sage Advice > Compendium
If the d20 roll for an attack is a 20, the attack hits regardless of any modifiers or the target's AC. This is called a critical hit.
If the d20 roll for an attack is a 1, the attack misses regardless of any modifiers or the target's AC.