Such boots should fit evenly over the entire foot, not squeeze, but also not dangle freely. Your toes should not touch the toe caps when the shoe is fully laced. It is recommended to take half a size more than you normally wear. This way, you can wear thicker socks and feel comfortable when your feet are swollen after a long hike. Be sure to consider not only the length of your foot but also its width.
It is better to try on the shoes in the afternoon when your foot is a little swollen. You can also try different pairs of socks right away (thinner, thicker) to see how it feels. I recommend spending 10-15 minutes in boots and walking a little in them. If, after this time, your feet still feel comfortable, you can buy this model.