You mentioned that your Date of Birth is 1st january1999.
You can definitely apply for the SBI Bank PO post.
Best of luck for PO examination.
Thanks for asking the questions.
To appear in SBI PO 2019 exam Candidates must be between 21 to 30 years as on April 1, 2019. Since your date of birth is 1 January 1999 hence you are not eligible to apply for the exam. I would suggest to fill out the application for the 2020 year. For more details regarding SBI PO eligibility criteria check here
SBI PO 2019 Full Practice Mock Test
Start preparing for SBI PO 2019 with S Chand Test Series