Awww... that is so lovely that you want to help! I am genuinely touched 🥰
I think I'd go for - help them to lie down, move anything that they could hurt themselves on and call an ambulance. Let the paramedics know exactly what happened - especially if they hit their head - and also how they fell. A seizure will have you keeling over backwards, a slump is more likely to be something else.
Unfortunately there's no quick answer - it depends on the person and the seizure.
Some people are absolutely fine and can just get up and carry on!
The person I approached yelled for a first aider, I remember them lowering me to the ground, I know they called an ambulance and used my phone to call DH and give the paramedics basic info.
Seizures can vary wildly - I don't jerk. I just go vacant, then rigid then keel over backwards. Afterwards I will be crying my eyes out, confused and probably throwing up 🤷🏼♀️
Some people will get a warning/aura like me, some won't. Some are fine after, some aren't. Some can become extremely combative so make sure you're safe yourself.
Don't Panic
Make sure you know where your towel is. (If you know, you know 😁)