I help friends with their kids pretty regularly, they have two boys who are five and two years old. I don't have a huge amount of experience with kids other than them, so I don't really know what's "normal" in terms of behaviour and expectations.
The five year old can be nice company and fun to play with, but seems to have what I'd describe as basically toddler tantrums about irrational things. If he wants something and it isn't done quick enough, or right, he'll progress quickly to full on screaming/shrieking or shouting, he'll throw things or push people, dissolves into inconsolable tears. This will be about things like not being able to do something on a computer game, demanding mummy/daddy do it, and getting frustrated that they don't understand precisely what he wants or say it will take a few minutes to look up how to fix it. Shouting do it now, or you're doing it wrong, then bam tears, screaming, stuff can get broken with the flailing around. He would run away to his bedroom and scream/cry for an extended period of time if left to it.
After school, tired and hangry, I appreciate kids will have hair-triggers for getting upset about things. But is that level of tantrum 'normal' and any suggestions for trying to help? Currently they try to talk it out with him and explain, but when it's irrational tantrums about things you can't instantly solve, difficult to try to head-off or fix in the moment. Just seems to end with both him and them in tears.