I doubt that adding a 51st state which is similar to California in terms of population size and ideological leaning is the brilliant move some conservatives think it it.
With Canada added to the mix, the center of political gravity in the new, expanded US would shift significantly to the left. With its current positioning, the GOP would have no chance whatsoever at winning the presidency or the House anymore if Canada became the 51st state.
It wouldn't be a state, the serious discussion right now is Canada joining with the USA in some form of union to form a common labour market & economy, which would look something like a
Protectorate. The USA would protect Canada both militarily & from influence or exploitation by foreign bad actors (the chief culprit here being the European WEF). In addition, the USA would control our immigration policy in return for us merging with the lucrative American economy & labour market. It really is a no-brainer.