Then you'd just be discouraging sex in your own home. Congrats! They decided to do it in the car or public bathroom instead, without your knowledge, and without the safety net you could have provided if anything went wrong.
Contributing to the deliquence of a minor is broad law.
You should check the local statutory rape laws applicable to you. In many places, there's an exception if both people are close in age and are both willing.
The main worry is how the other child's parents would react were something to occur. Also, your co-parent if they not on board with your decision.
There's something called "talking with your partner".
I've definitely done the talk, "box of condoms under the bathroom, no questions asked, give them to your friends if needed" but that is vastly different than tossing a box of condoms at a minor and telling them to have fun.
Sounds very hypocritical. I mean, why are you disallowing it in your home when you already offer condoms "no questions asked"?
You need to understand that giving permission is not encouragement, and that withdrawing permission is not discouragement.
You may not want your kids to have sex, but if they understand the risks and still want to, the best thing you can offer is safety and privacy.