[mothered]

generally speaking, if you're getting a 403, you're doing something that you're not supposed to and the client code isn't even receiving your requests (server software filter).

Precisely.

Moreover, It can also be a WAF blocking requests.

my friend is getting this error!
* Forbidden: You do not have permission to access this directory on this server

If permissions have been set server-side/back-end, unless you have access to alter/modify the permissions, you cannot do anything solely from a client-side standpoint.

great point. yes there is no way to change the permissions if you not on the server side.

I've experienced It when the WAF kicked In, and had to circumvent that to gain access.

The 403 does differ on how It's configured server-side, hence there's no hard and fast rules on how to handle each one.