I no longer own an LG device, but I'm pretty sure you can uninstall them. I've removed Facebook/Instagram from all my phones, even going back to my old G5.Which apps are a personal preference based on what you like to do.
Facebook and Facebook Messenger are often preinstalled bloatware. In that case you can only disable them and their update services.
Ditto for Instagram, but you might find it useful.
Ads are usually the result of adware being installed by mistake. Be careful of what you install and from where you install it.
https://forums.androidcentral.com/g...-list-known-apps-aggressive-ads-new-post.html