In the Legends novels we see that he standard laser cannons (e.g. the ones that come with the ship, ostensibly for defence against asteroids and pirates) can be fired from the cockpit.
A pair of smaller weapons on the upper hull was controllable from the
cockpit. Lando started keyboarding until he had established fire
control through a pair of auxiliary pedals beneath the console. Then,
turning sharply - and feeling for the first time the stresses of
acceleration as it piled his blood up in odd parts of his body - he
trod on the pedals, blasting away at three of the enemy as they
Lando Calrissian and the Flamewind of Oseon (set before ANH)
Later Han "rigs" his new quad cannons to fire from the cockpit. This is clearly not a normal feature of the ship, either the cannons or the fire control mechanism.
Two quad laser cannon turrets were located at the top and bottom of
the Falcon. The quad laser cannons were more powerful than the Ground
Buzzer. Although the laser cannons were more accurate when fired from
the turrets, Han had rigged them to a control stick inside the
Adventures in Hyperspace: Fire Ring Race (set before ANH)
“Who’s up there firing the blaster cannons?” Han asked.
“Luke,” Leia said, and Han looked down the hallway, confused. You
could fire the blasters from the cockpit, but only with greatly
reduced accuracy. Yet Luke had nearly taken Gethzerion’s head off,
with Han less than a meter away, while piloting this hunk of junk at
full attack speed.
The Courtship of Princess Leia (set 4 years after RoTJ)