Gravity "works" 24/7, and tissues always stretch with time and the relentless pull of gravity, especially when there's more weight (implants) to "pull." At 3 weeks post-op your scars are still very immature, and can be expected to soften, stretch, and mature over an average of 7 months. Maybe more, and maybe less, but still over many months, not weeks!
Since your incisions are still pink and a bit firm, and your scars are still maturing, you can reasonably expect that your internal capsule scars are healing/maturing at much the same rate. Once your skin incisions are completely pale, flat, and soft, then your capsule is likely completely healed as well, and after that, implant position is subject only to aging and gravity over the longer time span--the former takes months to occur, the latter years.
So the ultimate answer is that it depends on your present appearance, your goal appearance, and what you look like at 6-12 months post-op. Talk with your surgeon. If you are still noticeably high after healing has completed and all scar tissues matured (6-12 months) and you really want to drop your implant positions a bit, a simple operation to open up the lower pockets a tiny bit is possible!
But if you take "fluffing" to mean that your implants will somehow "expand" or look larger as time goes by, this depends on the degree of skin and muscle stretch that allows the "high, tight" look to become more teardrop and "natural." But any degree of "looking bigger" is often offset by true volume reduction as swelling decreases. Everyone is different!
BTW, "fluff" is not a medical term, and usually relates to what certain adult film "assistants" do in order to keep the male actors "ready for filming." Ahem. So let's just say drop and soften, shall we? Best wishes! Dr. Tholen