Is non-binary trans?
Often yes, not always: it depends on how each person describes themselves.
Under the most common definition, yes. Transgender describes people whose gender is not the one they were assigned at birth, and a non-binary gender is, by definition, not the binary one someone was assigned. Many non-binary people call themselves trans, and many trans organisations include non-binary people explicitly.
Why some non-binary people do not use the word
Some non-binary people feel that trans is associated with moving from one binary gender to the other, and does not describe their experience. Some have not transitioned in any visible way and feel they have not earned the word. Some simply prefer other words, such as genderqueer or enby.
None of those positions is wrong. A word belongs to the people who use it, and nobody is required to take on a label that does not feel like theirs.
Trans enough is not a real test
Transition does not have to be medical, social or visible to count. The idea that someone must look a certain way or have taken particular steps to be trans is a form of gatekeeping, and it hurts binary trans people too.
What it means in trans spaces
Most trans spaces, including support groups and t4t communities, welcome non-binary people whether or not they use the word trans. When a space is for trans women or trans men specifically, it usually says so.
In dating, the t4t tag includes non-binary people for most of the people who use it. T4T dating covers that in more detail.
How to talk about it
When you are not sure how someone describes themselves, ask, or use the words they use. 'Non-binary and trans', 'non-binary but not trans' and 'just non-binary' are all things people say. Pronouns are a separate question: some non-binary people use they/them, some use she or he, some use several.