Can we take Attack action when not in range of enemy?

Can you take the Attack action without attacking, just to get any side benefits?

For example, Blade Flourish says:

Whenever you take the Attack action on your turn, your walking speed increases by 10 feet until the end of the turn […]

In all examples the bard has a speed of 30 feet and does not have Extra Attack.

First relevant scenario:

The Bard and the enemy is 40 ft apart. If the Bard can take Attack action before spending all 30 ft movement, then he can reach the enemy and attack them with the added extra movement. If not, the Bard and the enemy is now 10 ft apart.

Second relevant scenario:

There is an enemy around the corner. The Bard might or might not know there is an enemy there. With the added movement from Blade Flourish, he will be able to walk around the corner and attack the enemy.

Third relevant scenario:

Same as second scenario, but he will only be able to walk around the corner without being able to attack. He does not know if he can reach to attack the enemy at the end of the turn.

Is taking Attack action allowed without being able to make an attack?