Dual Enrollment Credits & Stanford GPA

Hi CC! So i have a question. I’m starting Stanford in the fall; say I transferred credits for DE classes that I took in high school. How would this affect my Stanford GPA? Would the grades be converted to the Stanford grading scale of A+ - 4.3, A - 4.0 etc? To further that question, what if the grade on the college transcript is simply a letter? Thanks for any help provided!