My BMI is 38.4. Can I still get liposuction, BBL and tummy tuck?

There is no absolute weight requirement for undergoing fat transfer.
While there is no absolute number (lbs.) in terms of weight for undergoing liposuction with autologous fat transfer, the optimal candidate has reached a healthy and stable weight (preferably with a BMI less than 30, which is associated with a lower incidence of complications).
If you have reached a healthy stable weight (preferably with a BMI less than 30), the focus should be on maintaining. I typically do not recommend gaining/losing weight for the sake of surgery alone (weight loss for the sake of your health is a different story). It is important to remember that weight changes post procedure can potentially compromise the results of your buttock augmentation (as transferred fat can change with weight just as it could prior). If you plan on losing weight, I would do so before surgery and plan on maintaining afterwards.
With regards to your specific question, you would likely benefit from weight loss prior to surgery. At a current BMI of 38, you represent a significant surgical risk. Weight loss will not only optimize your candidacy but improve your overall outcome.
As always, discuss your concerns with a board certified plastic surgeon (ABPS). 

Thanks for your question. Your safety is of utmost importance to us. We never want to do anything that might jeopardize our patient's health. Unfortunately, your BMI makes you ineligible for cosmetic surgery at this time. High BMI poses high surgical risk and reduces the likelihood you will receive optimal cosmetic results. Patients considering cosmetic surgery should have a BMI of 30 or less in order to minimize risks and maximize results.
If you have been unable to reach your goal weight with diet and exercise we recommend you a Board Certified Bariatric Surgeon. 

Thank you for the question. The best advice you can get is after
consultation with a plastic surgeon. Ideally, you would like your BMI to be less than
30, however, this decision is individualized based on your overall health
status and what procedure you are having among others. The closer you are to
your ideal body weight, the better the results of the surgery and the less
likelihood of perioperative complications. Performing multiple procedures is common in selected group of individuals. Having said that, prolonged operative times are associated with increased risk of complications (e.g. blood clots in the legs, pulmonary emboli, etc). Best,
Pejman Aflaki, M.D.
Johns Hopkins-trained plastic surgeon