Yes, Virgil has a library with random bytes, from which you can get any other, e.g. base64.
There is a class VirgilRandom, which can generate both numbers and sequences of bytes. If you need to get a Base64 string, then the generated bytes must also be passed to the method of the class VirgilBase64::encode (detailed info here).
Take a look at the example for C++ which generates 128 bytes and codes in Base64:
auto base64Random = VirgilBase64::encode(VirgilRandom("personal data").random(128));