Amal from Jordan says she gets tired from standing, so she prays while sitting. What is the ruling?

We say regarding standing in prayer, if it is an obligatory prayer, then standing is a pillar of the prayer, but it is waived in case of inability or illness.

The Prophet ﷺ prayed sitting, and a group of his Companions also prayed sitting.

So we say, regarding standing in obligatory prayer, it is a pillar but is waived in case of inability. In her situation, she says she cannot do it and gets tired and so on, so we say in that case there is no harm for her to pray sitting. As for the voluntary prayer.

Standing is a sunnah in it, so if she prays sitting, she gets half the reward of the one who stands, and if she prays standing, she gets the full reward. And Allah knows best.