for example: the dialer, file manager, messenger/sms etc.

Eh, they're alright, but you can usually find something better on F-Droid. As far as I'm aware, they're mostly the AOSP apps with slight tweaks, so they might look familiar

Apps where I use the default:

• Calendar (alternatives on F-Droid, like Etar, are virtually identical)
• Camera (there's OpenCamera on F-Droid, but I don't know, not really using the Camera much)
• Clock
• Contacts
• Dialer
• FM Radio
• Messaging (doesn't look super great, but don't use it much)
• Recorder

Where I didn't write anything, there's probably something better out there, but I rarely use these apps.

Apps which I've replaced:

• Browser → Firefox
• Calculator → Calculator++ (probably overkill for most folks, but I do think the default calculator app is terrible on virtually all Android flavors)
• Gallery → Fossify Gallery
• Files → Material Files
• Keyboard → HeliBoard
• Music → Booming Music (pretty much just because I want album-shuffle)
• Trebuchet Launcher → KISS (personal preference)

im basically just wondering if they're like privacy friendly enough

Most default apps are perfectly cromulent and these I’ve replaced:

• Browser → uazo/cromite
• Trebuchet Launcher → Neamar/KISS
• FM Radio → Leotec Pocket Radio
• Music → mpv-android/mpv-android

Then for privacy, the default apps are as private as is required for their purpose. When it comes to apps in general, I don't install them if there is a webversion. I bookmark services in the web browser and then let the web browser handle privacy. Browser homepage is my bookmarks. uazo/cromite is very privacy friendly.

yeah sure, but fossify is better.

Replace the browser with Firefox or a fork, then yeah.

LineageOS isn't particularly privacy-focused. Without having checked, I would assume there's cruft in the codebase, like networking using Google's 8.8.8.8 DNS server, just because it's based on Android.

But the apps themselves generally don't even use the internet, so there's not much they can get wrong in terms of privacy...