In reply to Mountain Spirit:
> It will take a lot of time if I do not climb regularly.
Afraid so. So climb as much as possible!
> If I want to climb above my max grade (F5, Severe) outdoors, do I need to increase my physical fitness, strength endurance and power endurance?
You really, really just need to get more time spent on real rock. Leading, seconding, bouldering or top roping are all fine, although you probably want to be very careful leading and not start pushing it until you've spent a while climbing with more experienced people and they're happy with your gear placements.
I did a lot of climbing indoors before I went outdoors, and learning to climb outdoors felt like relearning everything. Holds look different, moves feel different, climbs form different shapes, you need to make different decisions, you forget all the technique that you've spent ages learning indoors, and because you aren't using the right technique, all the strength and endurance you've built up are no help. You watch little old men effortlessly solo routes that you couldn't do on a top rope and wonder what you're doing wrong...
If you get to a point where you've done a lot of outdoor climbing and you're moving elegantly and efficiently on rock then you might be able to push your grade by doing strength and endurance work indoors, but until then it'd be like upgrading the engine on a car with no wheels.