Suzuki is right – waterproof is probably too strong a word for most boots. I have used Obenauf’s LP leather conditioner which is wax on my leather boots. It works ok. My old man uses silicone which definitely works a bit better.
One other thing to consider is gaiters. If your pants are wet and you are hiking/walking that moisture is likely to work into your socks and boots. A gaiter is relatively cheap and will reduce the likelihood of soggy socks come end of day.