You redpill someone by dropping redpills. You don't debate them. You simply state facts when the opportunities present themselves. You can lead a horse to water, but you cannot make it drink. If your efforts fail on someone, give up on them. There is no time to waste on those not receptive to redpills. Plainly state your positions and drop facts. That is it. There is no "convincing."
You can increase the chance of your redpills being absorbed by being someone your target looks up to. Be older than the target. Be superior to the target mentally. They must trust you as a source of knowledge. If you frequently lie, exaggerate, misstate, or twist facts to suit your narrative, you will not be trusted and your opinion will remain just that: your opinion. If you are more fashionable, higher status, older, and more intelligent than your target, they will be eager to learn from you. It is extremely difficult to redpill your parents for example. You can do this by simply "being right." When it becomes clear to them that your worldview is more accurate because it has more predictive ability, they will gradually become more receptive to hearing and repeating what you have to say.
You must remember that the cards are heavily stacked against you. It is more profitable for your target to parrot leftist ideology. Society as it stands today is structured to reward leftists and leftist virtue signalling. You will not be successful with most, but you may be successful with few. Good luck.
Fucking amateur hour over here.