Polearm Master allows a PC to make an opportunity attack when an enemy enters within reach.
With the Brace manoeuvre, you can use a reaction to make an attack, expending a superiority die.
BRACE When a creature you can see moves into the reach you have with the melee weapon you're wielding, you can use your reaction to expend one superiority die and make one attack against the creature, using that weapon. If the attack hits, add the superiority die to the weapon's damage roll. Tasha’s Cauldron p.42
Do these features stack, meaning - can they occur simultaneously or on the same turn? What would be a way to make use of both of these character abilities?