Tuberous breasts. Would I need a lift or lower of the inframammary fold to achieve big round breasts? (Photo)

A side photo would help. Based on the front one you’ve provided, however, you don’t appear to have constriction of tissue around your nipples and you have a distinct breast fold. These are two traits that define the tuberous breasts. A straightforward breast augmentation may be sufficient, depending on whether there is no sagging present.

It's good to clarify the distinction between tuberous breast deformity and having naturally small, narrow breasts. Tuberous breast deformity is characterized by several specific features: a constricted breast base, which makes the breast appear narrow and elongated; herniation of breast tissue into the areola, causing the areola to appear puffy or enlarged; and a higher than usual inframammary fold, which makes the lower part of the breast lack fullness. It also typically involves some degree of asymmetry.
If you have small and narrow breasts but do not exhibit these other features, it’s possible that you do not have tuberous breast deformity. Instead, your breast shape might simply be the result of your natural anatomy.
For individuals with a narrow breast width (or footprint), achieving a round, full look through breast augmentation can be done effectively with careful planning:
Implant Selection: Choosing the right size and shape of implants is crucial. Round implants might be recommended to enhance fullness, especially in the upper part of the breasts.
Adjusting the Inframamary Fold: In some cases, lowering the inframammary fold allows for the placement of larger implants, which can help achieve a more rounded and aesthetically pleasing breast contour.
Consulting with a plastic surgeon is the best way to determine what specific procedures will help achieve your desired outcome. They can provide a detailed examination and tailor a surgical plan that aligns with your aesthetic goals.

You do have a short lower pole on both breasts that would classify them as tuberous; however, it does seem like your skin in the lower pole will stretch and fit a properly sized implant without violating the inframammary fold. Lowering the fold may risk a double bubble deformity but in your case it may be possible since it doesn't seem very constricted.