'become bulky' is correct and usable in written English.
You can use it when referring to a physical object or person becoming larger or thicker. For example: After months of weight training, his arms had become bulky.
Conventional permanent magnet flowmeters (PMFM) for large pipelines become bulky, heavy and have installation problems.
These PMFMs become bulky and heavy and are less sensitive for flow measurement in large pipes with diameter above 100 NB.
By rigidly adhering to design characteristics and material choices (graphite flow plates and metal end plates), conventional fuel cell designs have become bulky, fastener intense designs that have a high degree of manufacturing and assembly complexity.
Men's cardigans have become bulky enough to be worn as a jacket on their own.
If women lift weights, they'll become bulky and masculine looking.
However, the binder folders will quickly become bulky.
He writes: "As the newspapers have become bulkier and bulkier, as the sources of information have proliferated online as well as in print, there seems to be less space than ever for accuracy.
The analyses indicate that thermal management in the lower efficiency systems is very challenging and that the radiator becomes bulky if the stack temperature cannot be allowed to increase to 90 95 °C under driving conditions where heat rejection is difficult.
Although some have suggested that patients with a tumor-positive SLN who do not undergo CLND can be followed by ultrasound examination of the regional nodal basin to detect nodal disease before it becomes bulky and difficult to control, this strategy remains unproven.
Armour steadily became bulkier and heavier, forcing the breeding of more and more massive horses, until the combination rendered maneuverability nearly impossible.
The PCO2 values of 3a (Br−), 3a (TFAc−), and 3a (Tf2N−) were 11, 23, 53, respectively, indicating that the CO2 permeability increased as the counter anion became bulkier.
