The rule of thumb is 100m onto ground 200m onto water for a 99% chance of death.
At 25m if you land feet first there is a very good chance you will live and being a bridge, someone is likely to see you and ensure you're treated promptly, increasing the odds of living as a cripple on suicide watch further
I would look for something higher
More than 99%. 100% if you don't land on like a tree or a bush or something.
Buuuut you can't make sure to land on your head, unless you have a lot of experience.
Eh, people have survived falls at terminal velocity and people have survived places like the golden Gate Bridge and beachy head, I think 99% is pretty accurate for 100m.
If you could guarantee landing on your head from 100 m onto concrete you could probably get reeeaaally closeto 100%, but humans aren't very good at controlled free falling; at those heights you'll begin to tumble as you fall.
I just think it's dangerous to tell people a method is 100% when it's very much been proven not to be.
Unless you combine jumping with another method like anti-coagulants, OD, or an 80m rope for your 100m drop there is always the chance of landing feet first which very much not an assured death.
Humans take a lot to die at times
https://en.m.wikipedia.org/wiki/Nicholas_Alkemade this guy had trees and snow on his side but he fell, 5500m without a parachute and lived with only a sprained leg. Falling from 100m is very much in the realm of 99% chance of deaths and unless you're combining multiple methods you won't be able to reach that near 0% chance of failure.
It might sound pedantic, but when the results of failure include ending up crippled for life and/or institutionalised we should be striving for as close to 100% success as we can get and we should not be so arrogant as to think nothing can go wrong or stop our method of choice