In the link below you will find some of the treatments approved in the US for colorectal cancer in 2021, along with the main genetic mutations and other restrictions for use, if any.
The treatments ending in suffix "-mab" are monoclonal antibodies and therefore fall in the general categories of targeted therapy or immunotherapy.
Immunotherapy is a sub-category of targeted therapy where the monoclonal antibodies are used specifically to enhance the immune system to help it better fight cancer. Other monoclonal antibodies are used for different purposes, for example, to block the cancer cells from growing or duplicating, or to deprive cancer cells of food or oxygen, etc., but are not used specifically to enhance the immune system.
So, if you are interested specifically in immunotherapy, then what you would do is to look at the suffix of the generic drug name in the list below and check for "-mab". If the generic name contains "-mab" then it might be an immunotherapy (i.e., immune system enhancing). If the generic name does not end in "-mab" then the regimen is probably one of the standard chemo regimens that operate outside the context of the immune system.
https://coloncancersupport.colonclub.com/viewtopic.php?f=1&t=65284&p=507610#p507610Your father was on Folfox then on Folfiri, neither of which is immunotherapy. Which country/region are you located in?
Note: This list is only for colorectal cancer medications already approved for use in the US. There may be other immunotherapies approved in other countries, and there may be other immunotherapies that are not currently approved and that are only available now by participating in clinical trials.