Find a Thesis Topic
Find out now whether it has been done, not in your second year.
The expensive way to find out a thesis topic does not work is to find out in the second year. By then the reading is done, the method is chosen, and the discovery that a 2019 paper already answered the question — or that the data you assumed existed does not — costs months rather than days. Testing a topic against the literature early is a short exercise with a large payoff: it tells you whether the question has been answered, whether it is answerable with the resources a thesis has, and whether there is enough prior work to build a chapter on without there being so much that you are the hundredth person there.
What makes a good thesis topic?
Enough prior work to stand on, a question that has not been answered, and a method you can actually run with the time and access you have.
How do I know a topic is too crowded?
When recent papers already answer the sub-questions you were planning as chapters. That is a different problem from a topic being well studied.
Should I choose the topic or the method first?
The question, then the method. A method looking for a question produces a thesis that struggles to say why it matters.