I am unable to update iOS on my iPhone XS

Here is how to update: Update your iPhone or iPad - Apple Support

Here is what to do: If your iPhone or iPad won't update - Apple Support

You may need to use a Mac or Windows PC, and that is described in the links.

If your data matters and you do not have a current backup, then get a backup first, too.

What happens when you attempt to update?

Any error message?

What is the existing version of iOS?

Which device?