There are a lot of different ways to preserve roses depending on the look you want and how you'll display them. Here's an article that will help you start your research. Wishing you the best.
the easiest way would be to smash it carefully in a large book, put it in s few sheets of newspaper to help get the moisture out. You might change the paper a couple times per week for the first week or two or it could begin to mold.
Here are 8 ways to preserve roses and other flowers: https://dengarden.com/interior-design/how-can-i-preserve-a-rose
Hi Candy. Make your own preservative to extend the life of cut roses. Dissolve 3 tablespoons sugar and 2 tablespoons white vinegar Add 1 quart warm water. When you put the flowers in a vase, make sure the cut stems are covered by 3 or 4 inches of the prepared water.
This video is really useful
You can dry flowers, without pressing them, by using silica gel beads. This can also be reused lots of times.
See YouTube for tips on using this.
You can hang upside down to dry. Then you can display in a vase.
Dip them in paraffin wax
Here is a video that shows how: https://www.youtube.com/watch?v=uDuId6H8mPU
You could hang them up side down to dry out or you could dip them in Glycerin and let them absorb the substance or dip them in wax clear wax and they will last
I have pressed them, used hair spray to preserve them, and here's a post that might help you - https://www.save-on-crafts.com/ideas/dryingroses/
You could also preserve them in Silica Gel - It dries them out........Best wishes.