What you want to do is totally possible with UE. How good a game looks depends completly on you. For what you want to achieve I would start by looking at the related documentation:
Scalability Reference: will help you understand how to reduce certain effects.
Lightning is a huge factor when optimizing games. So you might want to take a look here:
Remember that each light can have or not shadows casted, so, again, it depends on you.
And finally, but not least, post processing is one of the biggest performance drains on most games, so you should look into this.
Most post process effects can be completly disabled, independently if you work in blueprints or in C++. Hope this helps and remember to mark this as the correct answer if it is what you needed. Have a great day!
