Yes. both Titanic and Olympic were Larger than Aquitania.
Hello there! I need to tell you that both Olympic Class liners and R.M.S Aquitania were massive and large ocean liners. Cunard's R.M.S Aquitania was actually longer and wider than the Olympic, Titanic and Britannic. See, the Olympic Class dimensions are we follows,
Olympic and Titanic: 882 FT, 9 IN (269 M) Width, 92 FT, 9 IN (28.19 M) and 45,327 (Olympic) and 46, 328 (Titanic) GRT. There speeds were also 21-23 knots.
Britannic: 885 FT, 0IN, (269.3 M) Width, 94 FT, 2 IN (28.7 M) and 48,157 GRT. Speed, 21.5-24.1 knots.
Now as you can clearly see, there massive ships, very luxurious as well. They may have not been as fast as Cunard's
Lusitania and Mauretania, but they were still fast. Now Cunard's Aquitania, is longer. Her dimensions are as follows,
Length, 901 FT, 1IN (274.6 M), Width, 97 FT, 0IN (29.6 M), 45,647 GRT and speeds of between 22-24, maybe 25.3 knots. So in terms of GRT (Gross Registered Tonnes), the Olympic Class is larger, but with length, width and speed, Aquitania is clearly longer, faster and wider - I sometimes nickname her, "Cunard's Olympic" as both ships had similar GRT and in some (not all places) the interior was somewhat similar. So it's fully accurate to say that Cunard's Aquitania is longer/wider and having a slightly nicer/more attractive interior and Britannic was larger in GRT (by approximately 3,000 GRT).
Please note - I am simply not a fill time expert in ocean liners, I am simply a fan and if likely 'an ocean liner nerd'. This was not comparing apples and oranges since all four ships were about 2-3 years older (except Britannic, she is 1 year older) than Aquitania, and people belive Aquitania's exterior is big and boxy, well it isn't, I actually prefer it (at certain angles) than Olympic, Titanic and Britannic's.
I hope this helped you.