If you have ILR (Indefinite Leave to Remain), you do not need to apply for settled status, but may do so if you wish.

You may want to apply for settled status even if you have ILR for the following reasons:

To benefit from enhanced family reunion provisions;
To have a digital status so you can prove your status if you lose your ILR document;
To make it easier to apply for citizenship if you so wish, without...