If someone adds me as a friend without a conversation first, how should I respond ?

Just assume they want something other than friendship. If they stick around you can sort it out later.

They might have similar interests as you and want to chat

Ha! Not sure how it is for the men here, but for me... it becomes an investigation! lol Too often, I find it's men with things we don't have in common...
Other times, I am surprised in a good way.

Do you mean you have never seen the person on posts or comments before?

Check out their profile. It will tell you a lot.

I typically just ignore them. 🤷

I consider talking back and forth on feed , for a considerable amount of time to be enough, after checking out profile,of course, for an add,you have no obligations to add anyone.
I rarely follow people,to be honest,just because they follow me.

Is it that big of deal are you that in demand and special you shouldnt be added without asking you first ?

Check their profile.

Any way you like.

Don’t add them.

You shouldn't

I generally ignore it or check their profile. If their profile has posts and they aren't gross I'll add them back. If it's empty or raunchy then ech no thanks

Do they add you or request your friendship?

They might like your posts and want to see all that you do

I just ignore them...

[big]Proceed with CAUTION!![/big]

Call the authorities.