The starcaster is quite a small guitar
I would suggest perhaps a classical guitar in full size they have huge necks or a telecaster.
I am a guitar teacher and I have many students come to me with this problem that can seem impossible at times to sort.
Also if your problem is hitting other strings when playing chords.
My tip: On the C chord your third finger will most likely be the culprit! it will be going at a slight angle and hitting the D string.
The solution: try pulling your thumb and wrist down slightly so that your hand is able to point the third finger down onto the A string at a better angle so it is not going over the D as well, do not over bend the wrist as it will damage your joints.
I find posture is the hardest thing to achieve and your tutor (if you have one)will need to guide you as words are subjective, however I hope I have been of some help.
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