I'm a huge Resident Evil fan and I'm fiercely loyal to the franchise but I have very severe arachnophobia so it's why I had to abruptly stop playing the original RE1 and I'm scared for the original RE2/RE3 because of having spiders even in 1990s resolution. I even play a modified REmake because of that phobia.

Would there be any way to modify the game to give an arachnophobia option or at least an arachnophobia mod?

I'm not sure if you're able to grasp how much additional work that would be, for a vanishingly small amount of people playing the game.

I can assure you that it won't happen. Someone doing a third party mod is the only chance something like that would be possible.

I'm pretty sure that GOG would not add that option, there isn't a manual in the game's folder for example.

I believe someone who knows how to program could delete the spides in the mansion, including that spider in the caves.
Maybe just delete them using an Hex editor? I have no clue.

Man, if I knew how to do it i'd make it for ya, but I can't.

That would be nice for him.

I also don't like spiders in real life, but in the game for me it is not a problem.

If this version is open source enough, it would be easier to replace the spider textures in the game for something else, rather than eliminating the objects. Or maybe it would be possible to eliminate the characters through scripting like if they were never there, it totally depends on how open source the game resources are.

Fear for dangerous situations like heights or animals like spiders is nothing you need to "overcome" because it exists to avoid injury or death, the only thing you might need is to replace fear for intent of action, in case your fear is overwhelming, because overwhelming fear defeats the purpose of your alertness instinct, it doesn't prevent you from the danger or harm but rather facilitates it. So for heights or spiders you get your instinct of fear first, and then you rationally realize you need to keep a cool head to overcome the dangerous situation.This is the way to manage a sane phobia without fighting your own natural instincts.

Most likely not sadly but you never know, there is however mods for RE4 and RE1 remake to omit or change spider looks for a less stressing experience.