Standardisation of iron(III) nitrate solution.

I am doing my chemistry project on the iron content of teas.
As a result I have had to prepare an iron(III) nitrate solution to make my calibration curve as a reference. I need to titrate this solution but everything I search up is using iron(III) nitrate as the titrate and not the analyte.
Can anyone help me to work out what chemicals and method I need to use to work out the Fe^3+ concentration in the iron(III) nitrate solution?
Or point me to some good resources which could help me work out the answer?

I am doing my chemistry project on the iron content of teas.
As a result I have had to prepare an iron(III) nitrate solution to make my calibration curve as a reference. I need to titrate this solution but everything I search up is using iron(III) nitrate as the titrate and not the analyte.
Can anyone help me to work out what chemicals and method I need to use to work out the Fe^3+ concentration in the iron(III) nitrate solution?
Or point me to some good resources which could help me work out the answer?

Personally I’d use the first of the three methods suggested by Nitrotoluene. The chemistry involved is quite straightforward- Zn reduces Fe^3+ to Fe^2+ and then the acidified potassium permanganate oxidises the iron(II) back to iron(III) with a very distinctive colour change (the purple solution of KMnO4 in conical flask goes virtually colourless since Fe^3+ and Mn^2+ are both pale and the concentrations of both will be low):
2Fe^3+ + Zn —> 2Fe^2+ + Zn^2+
5Fe^2+ + MnO4^- + 8H^+ —> 5Fe^3+ + Mn^2+ + 4H2O
For this, you will want to use sulphuric acid solution to make up the standard solution of KMnO4 (HCl oxidises to Cl2 with KMnO4, HNO3 is itself oxidising and leads to side reactions and many alternative acids like CH3COOH are too weak). All the chemicals you’ll need should be readily accessible in a high school laboratory.
As for why I’d pick it over the other methods, I’d say method 2 proposed by Nitrotoluene involves a much less distinctive colour change at the endpoint of the titration and method 3 involves a more annoying colour change to monitor (orange —> pale yellow), so spotting the endpoint is more challenging. You could always try adding another ligand to the iron(III) nitrate in advance to make the colour change more obvious (salicylic acid I believe forms a red complex with iron(III) ions) but this will end up diluting the analyte and making the calculations more tricky.