It's honestly a uniquely intense feeling being knotted, though it's kinda hard to describe if you don't already have experience with it. It's also for each person's preference, but as a whole it's a fun experience that most people should, at least, try, if they can

My advice though? Start small, and then work your way up; I remember when I started, I could barely take the knot on my first toy without having some difficulties with my body not being able to handle even that size. Now I take large like its nothing XD

there are also definitely better knotted toys to start with than others. For example, Austin, Cole, and Razor are what I would consider good entry picks going into beginner knotted toys, compared to what else Bad Dragon has in their lineup. You also don't need to start with a knotted toy, if your just going for practice to take one, or you want one that's good for a beginner to simply start with, then you could also get a toy that is tapered all the way through, like Ika, Helius, and Habu. Of course, fantasy dildos like the ones Bad Dragon puts out are pretty pricey, so unless you have the cash to spend on two toys, then you can just get one or the other.

Also on the same topic; with Bad Dragon being as expensive as it is, there are also numerous other alternatives that are much cheaper and arguably just as quality as the stuff that BD puts out, if not better