Hi, is there a method to scale up the modulus size and scaling factor for CKKS? For instance, can I switch from firstmodsize=40 to firstmodsize=50 and from scalefactor=30 to scalefactor=40？
You can hypothetically scale up a message, but this will not improve the precision by 10 bits (when you go from 30 to 40 bits). The precision cannot be improved even using CKKS bootstrapping (CKKS bootstrapping enables more computations but does not increase the precision).
In OpenFHE, we use same-size moduli (close to the scale factor) for better usability. Internally, one can use different moduli, but the scaling factor would have to be tracked manually, which would significantly complicate the usage of CKKS. The first modulus can hypothetically be changed (it does not affect precision, it only changes the maximum bound for messages), but again this would have to be done using internal tools of the library, e.g., we sometimes do it in scheme switching.
In summary, the simple, practical answer is no.