The most relevant platforms to interact with people in the space are:
Twitter is used to write short form content that either redirects to long form content like Medium, Mirror, Substack, … articles or it is content short enough to fit in a few tweets unless you write a 206-tweet long tweet (in which case @thereaderapp is useful to make long tweets readable).
Telegram is a single threaded chatting platform which is generally used for simple group chats and newsletters in crypto, as a developer there are a few groups which you can follow within your specific realm of interest or create group chats with friends in order to discuss various topics, create a learning group for a programming language, protocol, or topic, and more. Telegram is good for simple one-thread conversations where you don’t need to manage asynchronous communication.
Discord groups are useful once you have a big community, DAO, or friend group which you want to participate in. For developers there are various good groups like Buildspace, Developer DAO, and others. It is also used by different teams to manage contributions to an application, protocol or service. So for example if you become a contributor to an open-source project like Aave and you want to recommend a change to one of its open codebases and the change gets accepted, the coordination, and all the processes usually go through Discord. Many projects also help new contributors get started with building with a project and if you are learning something new it is a good place to ask technical questions.
Real life events
Although not available to everyone there are events hosted all around the world where people from different communities within web3 and crypto gather together in order to organize conferences, hackathons, parties, meetups, talks and more. Real life events are one of the best places to find like-minded people to become friends with, to get hired, to network with other interesting people in the space, to learn, to build new projects at hackathons and push your own boundaries, etc. It is underrated just how much you can grow as a developer if you surround yourself with people that have the same properties that you want to acquire for yourself. The people around you can push you to grow and take you to new heights as they expose you to new challenges and help you along the way.