Way back in the early 80s I had extreme New Wave hair cuts and colors, from Boy George Red to purple. Back then the product of choice was called Cellophane because it was a clear color. My hair is still too brown to get much out of temporary colors so I have to bleach first but there are all sorts of them out there. Mostly I can do over washes with various shades of red. You can do it yourself or have it done in a salon. Here's one version:
https://www.amazon.com/Keracolor-Cle...-7&tag=mh0b-20
Then my son went through a couple years of green hair in Middle/early high school. We've tried some koolaid colors, but mostly bought them at Hot Topic at the mall.
https://www.hottopic.com/accessories...ir/hair-color/
Here's a new to me product that might work well for you (I did a search on temporary hair color):
https://www.amazon.com/Christmas-Tem...8192458&sr=8-7
I think these "hair chalks" would be the way to go for special occasions or when you just need a lift.