Sort of. When you employ some type of off-hand fighting as a bonus action, it gives you one extra attack on your turn, not your multiple attacks. When you get the multiple attack ability at higher levels, you still can get one additional attack per turn as a bonus action. What you don't get is one additional bonus action on every attack. Example: Drizz’t the Ranger, on reaching 2nd level, chooses Two-Weapon Fighting as his Fighting Style with double scimitars as his weapon. He can make a second attack as a bonus action with his off-hand and still keep all modifiers for proficiency and ability. When he reached 5th level, he gets 2 attacks. Because Drizz’t has Two-Weapon Fighting as his Fighting Style, he gets one additional attack per turn as a bonus action. Therefore, Dirzz’t has a total of 3 attacks per turn and has full modifiers for proficiency and ability; he doesn't get 4 attacks. Two-Handed Fighting/Dual Wield don't actually double your attacks, they simply add an attack as a bonus action, only once to your turn. Were Drizz’t a fighter instead of a ranger, he would have even more opportunities for multiple attacks at higher levels. At 11th level, Drizz’t would normally be allowed 3 attacks per round, but, because he has Two-Weapon Fighting as his Fighting Style, he can make a total of 4 attacks per round. At 20th level, Drizz’t would normally be allowed 4 attacks per round, but, because he has Two-Weapon Fighting as his Fighting Style, he can make a total of 5 attacks per round. After 20th level, Drizz’t wouldn't be able to get any additional multiple attack benefits and 5 attacks per round would be his maximum without magical aid.