There are some good tutorials you can find on the DevForum here:
https://devforum.roblox.com/t/making-an-fps-framework-2020-edition/503318
https://devforum.roblox.com/t/the-first-person-element-of-a-first-person-shooter/160434
They’re both around a 10-20 minute read, and they have a test gun you can build off of.