It is difficult to be sure from your question, but you may have a slight misunderstanding of "Ct" value.
Ct stands for cycle threshold¹. In a real time polymerase chain assay, a sample is analyzed using fluorescent probes which generate light as more copies of viral genetic material are created.
This image adapted from Raaban et al (under CC-BY 4.0) shows how this works:
Thus, as fewer cycles are required to detect the signal, more viral genetic material was present in the initial sample.
Some authors have described Ct values of 17-24 as "high viral load" and 25-35 as "moderate viral load"², but each test manufacturer is likely to set their own cutoffs for their specific assay.
While these is relatively good evidence that lower Ct value correlates with more severe SARS-Cov-2 disease¹, there is not a direct relation between Ct value and viral load in the patient. Other factors might include how the sample was collected and diluted. As Raaban and colleagues note:
The pre-analytic variables include collection technique, specimen type, time of sample taken and viral kinetics, the difference between the viral load in URT and LRT samples, transport and storage conditions before the testing, and the specimen age.
Thus, there is no reliable way to determine how Ct value will change over time. It might increase if the virus is being successfully fought by the immune system. However, the Ct value might decrease if the virus continues to successfully replicate.