2017LHP - there are quite a few threads on post pitching icing. There are definitely proponents of the practice, but there are a lot of people who do not advise icing. There are some pretty interesting debates in some of the past threads, if you have time to read through them.
My 2018 still ices. He uses an arm sleeve that has slots for ice packs. They are pretty inexpensive at any sporting goods store. I don't think it really does much for him physically, it's basically a mental thing at this point. If it makes him feel better mentally and I don't think it's really doing any harm (it may slow down recovery very slightly), then I don't have a problem with it. The main factor in his recovery are his post-throwing exercises and routines.
If the right people see this thread and want to jump in, you may get a good debate on the positives vs. negatives on icing.