The vast majority of the international community considers the settlements illegal under international law, though Israel and the US under the Trump administration dispute this interpretation.

And from the BBC:

Annexation is the term applied when a state unilaterally proclaims its sovereignty over other territory. It is forbidden by international law. A recent example was Russia’s annexation of Ukraine’s Crimea peninsula in 2014.

By and large, Israel has been warned by friend and foe alike not to go ahead with annexation. There are fears that such a move will put peace between Israel and the Palestinians even further out of reach.

The UN’s Middle East envoy has warned that Israeli annexation and Palestinian counter-steps “would dramatically shift local dynamics and most likely trigger conflict and instability in the occupied West Bank and Gaza Strip”

Something makes me think Israel shouldn’t be occupying the West Bank.

Edit: typo