The most important aspect to loneliness is remembering that you are never actually alone. It is a universal human experience that can pop up for everyone in any situation whether you are by yourself or in a big group.
Can you acknowledge and identify when you are lonely? Acknowledging is always the first step in confronting your feelings.
Remember the moments when you weren't lonely and appreciate them for what they were. You haven't always felt lonely and know that the feeling will pass.
Whether the community is online or IRL, join a community where you can feel seen and supported.
Walking or moving your body in some way will transition yourself outside of your thoughts and into your body sensations. Change the energy!