It's not just you! And when I see someone else's small child doing this, all I think is 'oh dear, they're having a tricky day' (both the parent and the child).
Firstly, the basics – are they tired, hungry, need the toilet, hot/cold, poorly? Any changes in their life recently? My generally-very-reasonable-for-a-toddler DD1 threw a few of these in the months after DD2 was born, despite adoring her baby sister. There were a good few more over bedtime. (She still resents that we need to sleep at 4.5 years old, but manages said resentment much better, although we still get the occasional brief strop over it.)
How does he respond to 'toddler's choice', so like getting in the car, do you want me to lift you in or do you want to climb in yourself? Do you want to put your shoes on first or your coat? Playful ways of doing things (hop to the car like a rabbit, stomp like a dinosaur) also help for us. I do then get to 'I'm going to count to three and then I'm going to choose for you', but even then you can sometimes make it a 'fun' choice, so I choose flying to the car like a rocket, i.e., I'm going to carry you, like it or not, but zooming motions and rocket noises still sometimes head off the tantrum.
I've also found that if they're losing it, past the point of giving choices or counting to three, and something has to happen, it's often best to do it quickly and get it over with. It just seems to build and build at that point, and scooping them up and into the buggy/out of the bath/whatever as quickly as possible once the tipping point is reached seems the kindest way through it for us.
I would say that the flip side of that is if they are trying to get themselves calmed down – I would always try to support them in that if at all possible rather than pushing through to whatever needs to happen (recognising that occasionally time pressure is such that you really, really can't). So I give cuddles, give a bit of space, sing, reassure them that I've got them and I'll help them, whatever works for them. DD1 sometimes used to be able to nod or shake her head when asked 'would X help?' when trying to stop tantruming.
Sorry, that was long, but hopefully something in it is helpful, if only the solidarity.