It exists as much as the LGBTQ community in general exists. Neither one is a monolith, and both are peopled with people from all walks of life. However, all trans and non-binary people have in common that their gender is incongruent with the way they were born. We also have in common that a lot of people misunderstand, hate, and persecute us because we are all different from them in the same way.
Some trans people are more likely than others to reach out and help other trans and non-binary folx, but I believe being there for others is a big part of what it means to be part of a community. I help facilitate a trans support group, am on the board of directors for a transgender support, advocacy, and education organization, engage with and encourage transgender and non-binary folks online, and write about what it means to be transgender from my perspective.
In short, I try to contribute to my community. I think as long as trans and non-binary people are willing to connect with and support others there is a transgender community.