Possibility of repeating 9th grade in TX public schools?

(I posted this in r/texas as well but thought I should post it to the Houston subreddit as well)…

Hello!

Our son attended 9th grade at a charter public school this past year. Due to a number of factors (having fallen behind during covid, family circumstances, etc), he didn't perform well across most of his classes. We are wondering about the possibility of having him repeat 9th grade so that he can have a clean record when applying for college. Does anyone know if something like this is possible? We inquired at our local public high school (where we were thinking of enrolling him this year) and they said that they can't do that, they will just look at the number of credit hours and place him accordingly (more than 5.5 credit hours or something like that means he gets sophomore status, and he'll just have to repeat the courses he failed but as a sophomore).

Does anyone know if there's anything we can do that might be possible in order to have him repeat and get a clean record? Based on online research there do seem to be provisions for repeating a grade, but limited mostly until 3rd grade. Is there anything we can do for 9th grade? What if we tried to take him to a private school — might it be possible to have him repeat 9th grade there and then based on that transcript take him to public school next year?

Any advice would be appreciated! Thank you!