The specific typeface is usually a modified version of or "Huippo." However, because IbisPaint has a limited default library (mostly standard serif/sans-serif), you won’t find "Poplar" sitting in your text tool.
But here is the burning question: Can you get the iconic Oshi font on IbisPaint? oshi font ibispaint
Whether you are drawing your favorite Hololive talent, a Nijisanji liver, or an indie VTuber, that specific typography has become the visual shorthand for hype, support, and "favorite child" energy. The specific typeface is usually a modified version