I'm not sure that I would use the term "forced", but friendship can absolutely form between people who, left to their own devices, may not have given each other a chance. The way we present ourselves toward strangers differs from the way we present ourselves toward friends, and this can have an unintended filtering effect that may not necessarily correlate with compatibility.

Some of my most treasured friendships are with people I was "forced" to get to know via school or work. They are people who, from a certain perspective, have very little in common with me — but when we got to know each other, we discovered that our differences (like cultural background) were only skin deep, and we actually have a whole lot in common in deeper ways (like innate personality).

Some of these friendships took a very long time to bloom. With one of my closer friends, we only became friends after years of having to work closely together—but when it finally happened, we became the kind of friends-for-life who never truly drift apart. Left to our own devices, we never would have become friends because our acquaintance-personalities are not very compatible, even though our friend-personalities very much are.

Of course, this can go the other way as well. It is common to meet people you hit it off with right away, and then later discover you don't actually get along with as you become friends.

What do you define as friendship?

What do you define as force?

Do you feel that you've had meaningful "organic" friendships before?

Agreed, forced is the wrong word. I think maybe thinking of it as fostered or purposeful vs organic friendship. You can't force someone to be your friend but you can purposefully spend more time with someone. I did that recently with a person I got introduced to and it worked out well. We met at a neighborhood party and I really liked his personality and wanted to hang out more. I learned he liked biking, as do I, and invited him on a ride. Turns out he was even cooler than at the party! We decided to bike with more frequency together and I learned that he open water swam and couldn't find people to go with him. Open water swimming scares me but I thought, hell I bet I can do that and then we might end up closer. Turned out I was right. Locally he's one of my best friends now.

You can put yourself in the position to hang out more, but it doesn't mean you'll get along. But if there is alignment there you can definitely foster it so that you become closer friends than you would have otherwise.

I mean “forced” is the wrong word and wrong attitude to have about it. Friendships just like other relationships do often take work though. If you don’t normally find yourself in the same place as someone you have to make time to hang out with them. Typically a common interest would be useful so you can have something to do besides talking while you get to know each other.

War buddies can be friends for a life time.

Arranged marriages sometimes end up with life long friendship even where romance doesn't happen

Childhood friendships are basically forced interactions that eventually turn mutual

High school buddies are in my opinion some of the very very best that life can offer

Meeting romantic partners at hobby classes that run long enough for the shy introverted people to shine

I could go on. In fact friendship don't happen for me unless they are repeatedly scheduled. ADHD and introversion and face blindness going on here: I need the same content same people and scheduled to even be able to link interactions to the same person.

Friendships often form between children who are neighbors, who go to the same school, or maybe go to the same summer camp. But I would call that creating the opportunity for friendship to arise rather than being forced. It can go the other way, too.

It seems similar for relatives, like cousins? You see each other pretty often, but you might or might not get along.

If by forced you mean “through effort” then yes. You can form friendships with people that you would think aren’t “compatible” with enough extra effort. Now I’m going to controversial with my next sentence…

The extra effort only has to come from one side. Something I noticed in general is that there is a reciprocal effect even if one side is less active about it. I’m not saying there does not need to be effort from both potential friends, but I think only one side needs the “extra” effort.

I think there is some truth to the story of Gilgamesh and Enkidu. My childhood best friend and I hated each other at first and fought a lot, we were however from the only two Slavic immigrant families in the apartment complex and our parents met a lot. I don’t know who put in more effort, but after a lot of crazy fights, we became best friends. I think that childhood experience taught me to fight through the barriers that some people put up (on a deeper level, also the barriers you put up for yourself). You need some force there.

Yes, absolutely. Two people can choose to spend time together and foster a friendship, regardless of the fact they might never spend time together “organically” (i.e. without going out of their way and deliberately choosing to).

If anything, building a friendship this way could be particularly rewarding because you know you are friends out of a mutual choice to become so, rather than out of happenstance or convenience.

Depends, I have an acquaintance that's in the same climbing group of 15-ish people.
Apparently he considers me a friend ... He is definitely not mine as I don't like the fellow.
I'm just accepting of him as drama/tension is not needed, specially not when we're on a longer trip.

So in that case, no he can't "force" a mutual friendship with myself.
But he is growing a friendship with some of the other members of the group. So in those cases, yes he can.