When setting IsDynamic to true, the TrueType file is embedded in the asset and rendered on the fly using FreeType. It seems weird to then have to embed the file multiple times (via a different SpriteFont) for each different font style (e.g. bold, italic, etc.) when the base TrueType font already has the information required for the different font styles. It would be good to see some additional DrawString overloads with style options that are only used when IsDynamic = true.
Edit: I’ve added this to Github: