I worked with a great company when helping a relative downsize/move. Graceful Transitions -- they helped with so many things and would have done more had I asked them too.
They helped my relative decide what to take/what would fit in their new space and moved it, then packed up and sold/donated or disposed of everything else.
Graceful Transitions
https://www.gracefultransitions.org/
301-799-4321
We had identified a few things to go to specific spaces, otherwise they took it all to their warehouse and they determined what could be consigned, what could be put in an online estate sale and what would be donated. I didn't need to make any decisions after deciding what we would keep.
They would have shipped items to other family members or stored items for us if necessary.
It was very flexible and easy. I met with them once to get an estimate (1 hour) and then it was a two day process - 1 to pack and move what was moving/staying with the relative and the second day to pack everything else.
I received an accounting of everything- itemized receipts for everything donated and sold, checks mailed to where we asked for what was sold. They were efficient and lovely to work with.