Buffed Inquisitive (XGtE)

As an archetypal Inquisitive, you excel at rooting out secrets and unraveling mysteries. You rely on your sharp eye for detail, but also on your finely honed ability to read the words and deeds of other creatures to determine their true intent. You excel at defeating creatures that hide among and prey upon ordinary folk, and your mastery of lore and your sharp eye make you well equipped to expose and end hidden evils.

Attentive

When you choose this archetype at 3rd level, you gain proficiency in Investigation and in Insight, if you don't already have it. Your proficiency bonus is doubled for any ability check you make that uses either of those proficiencies.

You studied the behavior of your suspects and you know how to approach them in the best way, to get to know what you want. What you might lack in charisma you can make up for with you knowledge of how people think.  Whenever you make a Charisma check, you gain a bonus to the check equal to your Intelligence modifier (minimum of +1).

Ear for Deceit

Whenever you make an Insight check, treat a roll of 7 or lower on the d20 as an 8.

Eye for Detail

You can use the Search and the Study action as bonus action. You may use Search to gain information about a weak point of a humanoid or you might be using Study to recall information about a creature you encounter.

Insightful Fighting

At 3rd level, you gain the ability to decipher an opponent’s tactics and develop a counter to them. As a bonus action, you can make an Insight check against a creature you can see that isn’t incapacitated, contested by the target’s Deception check. If you succeed, you can use your Sneak Attack against that target even if you don’t have advantage on the attack roll, but not if you have disadvantage on it. 

This benefit lasts for 1 minute or until you successfully use this feature against a different target.

Steady Eye

Starting at 9th level, you have advantage on any Wisdom (Perception) or Intelligence (Investigation) check.

Your expecting movements frightens your enemies. Creatures selected by your Insightful Fighting feature have disadvantage on any attack rolls against you.

If you use your Uncanny Dodge you may now additionally try to apply your Insightful Fighting feature to the attacking creature.

Unerring Eye

Beginning at 13th level, your senses are almost impossible to foil. Within 30 feet you sense that if an effect is attempting to trick you, but you gain no insight into what is hidden or into its true nature.

You gain blindsight within a range of 30 feet and truesight within a range of 5 feet.

Eye for Weakness

At 17th level, you learn to exploit a creature’s weaknesses by carefully studying its tactics and movement. While your Insightful Fighting feature applies to a creature, your Sneak Attack damage increases by 3d6. 

Additionally the number you need to roll a critical hit is reduced by 1 on every creature affected by your Insightful Fighting feature.