Dear @Sebghat,
Welcome to the Wefugees Community and thank you for your question.
The process and the chances for permission depend on the individual circumstances and your current status. If you are still in the asylum procedure, you have to submit a so-called "Umverteilungsantrag" to the immigration office (Ausländerbehörde). I couldn't find a corresponding formular at the website of the immigration office in Koblenz - but this one is provided by another one in Rhineland-Palatinate. I found information saying that you have to submit the "Umverteilungsantrag" as well at the immigration office which would be responsible at the location you want to move to (Frankfurt). In any case, please consult the immigration office in Koblenz to be sure about the right procedure.
If you are holding a residence permit as a refugee (or Subsidiary Protection) which includes a so-called "Wohnsitzauflage" for three years, you have to apply at the immigration office to remove the "Wohnsitzauflage" (residence requirement). If you give work as the reason for the respective removal, your future employment should contain at least 15 working hours per week and a net income of minimum 820 EUR.
I hope this helps and please don't hesitate to get back to us with any further questions.
All the best,
Meike