Most temper tantrums happen in children from ages 15 months to 4 years of age because the child or toddler cannot handle the frustration and disappointment of being told no over things or just being frustrated and disappointed in just about anything.
But yes even 5 to 6, 7 and yes even 8 year olds can have temper tantrums when they are told no they cannot have this or no they cannot do that etc.
An 8 year old and even 5, 6 and 7 year old can handle frustration and disappointment much better than say a 15 month old or a 3 or 4 year old.
But still they are still learning to handle things and eventually the temper tantrums will stop.
If an 8 year old or even 5 year old is having a temper tantrum then you should force them to sit in timeout and or give the child a spanking to show them that temper tantrums are not gonna get them what they want.
I had a 5 year old kid throw a tantrum in a store and I gave him a spanking right then and there and then he stopped with the tantrum because he didn't like a spanking.
Then when he was 8 he was gonna have a tantrum over something again and I spanked him again before he even had the tantrum and he stopped and decided he didn't want to get spanked anymore in front of people.
But yes 8 years can have tantrums however they may not kick and scream as much as a toddler or younger child would.
A child having tantrums over something even as late as age 8 is normal and something parents should expect to have to deal with.