A concrete starting point
Scale degrees: 1 2 3 4 5 6 b7
C D E F G A Bb C
Compare centers, not just starting notes
C Mixolydian shares its pitch classes with F major. A shared collection does not make those two centers interchangeable. Play a quiet C pedal, repeat the tonic and end short phrases on C. Then compare the same notes with the parent-major tonic emphasized. A scale diagram lists pitches; it does not establish the harmonic center of a performance.
Try a focused comparison
Compare C7 with Cmaj7. Only Bb versus B changes between those two written seventh chords; the third remains E.
Write the pattern before speeding up
Use the formula 1 2 3 4 5 6 b7 relative to a C major scale. Keep the seven successive letter names and adjust their accidentals. First play the collection slowly upward and downward, including the upper tonic, then improvise a three-note response with a clear ending. Change one degree at a time when comparing a parallel mode. Correct spelling makes that degree relationship easier to see than a chromatic list of piano keys.
Put it into practice
These examples describe explicit written notes and relationships. A diagram or generated phrase does not replace listening to a complete musical context, choosing a comfortable register or checking a physical technique with a teacher.