Two cats can keep each other company, so it isn't so much of a problem as
if you only had one. However, for that length of time, you really need
someone to spend as much time as possible with them, ideally at least an
hour or two twice a day at the very least. The sitter needs to play with
them and keep them company, not just pop in, feed them and disappear
again. He/she needs to be someone they know and trust and are happy
around.

Do they have access to the outside, such as through a cat flap..? If so
then they can at least get out and about as normal.

Cats are creatures of habit, they detest changes to their routine. You
need to disrupt their lives as little as possible.

Hope this helps,

Ivor

If you can afford it, I'd suggest having the sitter come in twice a day.
That is what we do when we go on vacation.

I have done this many times and my 3 cats are fine as long as someone is
checking on them they should be fine.