When will my baby sit up is one of the most commonly asked and answered parenting questions on google!
At around 6 months your baby may start sitting up unsupported for a short period of time. Of course, not all children are the same so giving them anywhere between 5 to 8 or even 9 months is normal and okay. To learn to sit by herself, your baby needs to master balance. You can help by propping her up safely, with cushions on the floor, to ease her into strengthening those abdominal muscles.
Source: https://www.news24.com/amp/parent/baby/babycare/19-baby-questions-you-google-most-answered-20180807
