One of the truths about secondary sex characteristics is that very often, you can obviously see them. Another reality is that for many trans and gender-expansive folks, the presence of some characteristics, or the lack of others, makes us feel dysphoric. Unless and until we choose hormonal and/or surgical transition, it can be important to find ways to change our appearance.
And there is a growing industry to provide us with the tools to help. Sadly, these are not always in financial reach for everyone, although it is often possible to find inexpensive versions of many things. And using these may not only help us with dysphoria, but also helps us to pass in a society that is quick to police gender.
For trans masculine folks, there are ways to bind the chest, to make it as flat as possible. For trans feminine folks, there are ways to tuck the genitals out of the way to hide the package. For both of these, it's super important to know how to do these safely.
In terms of prosthetics, there is a wide range of prosthetics for both trans feminine and trans masculine people. For trans masculine folks, there are realistic packers to provide a bulge, stand-to-pee devices of varied sorts, as well as realistic prosthetics used in erotic play. For trans feminine folks, there are breast forms, hip forms, and vulva/vagina prosthetics, which also help with tucking.
It can be somewhat overwhelming diving into this realm - there are a lot of possible choices. The most important thing is do some research, and experiment. Try out different options, and see what works. See how you feel - notice what emotions arise in you as you use these. Notice changes in your dysphoria, if you have it, and your own sense of yourself. Notice any changes in how others respond to you.
Using these tools aren't the complete answer - in fact, nothing is the complete answer. But they can be super helpful along the way.