Welcome to the Wefugees Community and sorry for the rather late reply.
Unfortunately, I am not an expert on these types of residence permits and tried to make some research. Do I understand correctly, that you hold a residence permit according to section 16f of the German Residence Act to make a language course in Germany? Checking this table (published by the GGUA in Münster), it says actually that "switching" from a residence permit according to 16f to a residence permit according to 16a (vocational training/"Ausbildung") is only possible in exceptional cases. However, starting to study and applying for a residence permit according to section 16b might be an option.
Am I right on this dear @mbeon-Christine or @mbeon-fardeen?
In any case, I would highly recommend you to consult a migration counselling office to discuss your individual situation.
Please also don't hesitate to get back to us if you have any further questions.
All the best,