No, the number of integer and string variables are fixed in TRiLOGI.
However, you could use a separate program to save string data into the EEPROM using the SAVE_EEP$ command and then in your actual program, load the strings from the EEPROM using the Load_EEP$. This allow the PLC to select the suitable string to use by means of an index to Load_EEP$ and you can treat it as if it is an array of string constants. Even for the standard EEPROM version this can be used to optimize use of string variable and reduce program size. With the M2018P option you have more than 300 strings to play with.