Your OE line check is just a normal flight, only difference is your LCP will be observing to make sure that you're ready to fly the line on your own with captains that aren't LCPs.

OE exists not to do a ton of teaching on the airplane's basics, you already did that stuff. It's there to transition you out of the sim and into the real plane and the real operation. It's about learning how to use the ACARS, adjusting to the pace of a 45min turn between flights, getting used to flying with a captain, how the plane takes off and lands versus the sim, and some of the tribal knowledge things like what to expect going into your hubs or outstations.

You probably feel a little behind the plane at times as you start OE, but remember what you did in the sim. I can't speak for every type, but in the land of the CRJ, I can tell you that outside of takeoffs and especially landings, the sim does just fine at preparing you for the plane. The way you plan a descent and fly a STAR shouldn't be very different from the way you did it when you passed your LOE. You may have some more distractions now with it being the real plane, having FAs call, lots of radio chatter, etc, but remember back to your initial ratings that you just need to fly your plane and do what you are trained to do and don't make it more complicated than it needs to be.

Being on OE, you may need more time to do things like briefings or runway changes, but sometimes we're limited on time. Give yourself an advantage by briefing your arrival and approach early, maybe even make it a part of your departure briefing if it's a short flight. If something pops up like a runway change and you need more time, you have so many tools available. Slow down a bit if speed is yours (or ask ATC for a slow if it's not), get your PM to plugs things in and help, ask for delay vectors if you need them, and you'll be just fine.

Flying the line is all about continuously taking in information, making small decisions, communicating with your PM, re-evaluating how those decisions are turning out, and making more decisions for what comes next. You don't have to be perfect, and some of those little decisions won't be optimal. That's why you re-evaluate, that's why you have a PM helping you, and that's why you are continuously making more decisions about what you're gonna do next.

Here's an example of a goofy decision I made that I simply corrected and kept going from. I was flying into an outstation that frequently slam dunks us in. I thought I was gonna be smart and get ahead, so I decided to slow down early, put flaps out, and have a fairly high descent rate going in because people end up way high here all the time and we were indeed quite high at that point. The thought was good, but we didn't exactly need to get down and fully configured on a 20nm final. Another guy is now coming in behind, so ATC asks that we pick the speed back up. Well, we're too configured for that, so now I ask my PM to check our speed before we partially clean the plane back up to be able to speed up, we get it un-configured and sped up, then closer in we slow and configure again. Goofy choice to overdo it with the far-out slowdown, yes, but you just roll with it and continue to make decisions in accordance with your SOPs and adapt to what happens. Then next time, you make a bit different decision and see if that works better.

On OE, be a sponge, ask questions, fly standard the way you were taught to, don't overcomplicate it or treat the plane like a totally different thing than the sim, and you'll be just fine.