For example the UK was threatened at various points with having its electricity supply be cut off, having its planes be banned from overflying Europe, having Sp

For example the UK was threatened at various points with having its electricity supply be cut off, having its planes be banned from overflying Europe, having Spain seize UK territory like Gibraltar, and the EU did impose major financial sanctions against its key industries. The EU also likes to rope in US Democrat Presidents to threaten or suspend cooperation with the UK in various ways, if it doesn't do what the EU wants.