I am 24/Male and I have been riding since a year. Recently endurance riding has interested me. I have done two rides of 20 km each. Now I am planning for a 46 km ride.l My question is, should I go for it? or should I do some more 20 km rides?
Go for it - you're young and riding over the last year will give you an idea of your capabilities.
Do make sure your bike is maintained - having a mechanical is no fun. Take your spares/tools and food and water.
If the distance is challenging, think of it as an "out and back" which is each-way only 3 km longer than your normal rides. It becomes two rides in one day, with a bit of a rest at the half way. For me, there's a nice pie shop about 60 km away, so that's two rides with a 30 minute light-lunch stop in the middle.
Pacing is good, don't go too hard out in the first half. But the rest at the half way will help a lot and the ride home will always feel shorter than the ride out.
You'll never find out what you're capable of if you keep doing the same trips and distances. Extend yourself and push some limits.
The key is going to be how you felt after those 20km rides.
Assuming you were OK, the longer ride should be fine though you'll be tired and you'll ache in unexpected places. If you had any pain on the short rides you need to deal with that first - probably by adjusting the bike. Going from a 1 hour to a 2 hour ride (roughly, assumed times) you may well want to carry (more) water and an energy snack just in case.
I've been where you were 3 years ago.
Basically you can keep going. Your body will tell you it's limits. Make sure you listen to it. Aches and pains in your joints or tendons are an important signal not to be disregarded. Muscle ache however is a sign that you're improving. By going for longer distances you'll train your body in several ways and you will be able to go further and further.
A good rule of thumb is, if you are comfortable riding distance X then you can also do 1.33 * X if you have to. This is generally the advice I read when people want to reach a set distance. So if you want to do a 100km run, then train to be able to do a 75km run while coming home feeling ok. Once you reach this point you are ready to do the 100km.
So in your case if you are now comfortable with 20 you can probably do 25 and come home tired. Once you're comfortable with 25 (should take only a few trips) you'll be good for 33. and so on. The first few steps up will only take several (2-4) trips. Once you reach 60-80km distance it will take longer / will take more training to be able to increase though.
However, if you've been doing these 20km rides for a year you probably are already coming home very fresh / not tired at all. so you probably can skip a step or two. Before going on the 46km, see if you can do 34 and check when you get back if you are tired or exhausted. If you're just tired then you're ready for 46 :)
Once you go for multi hour bike rides I can recommend you start looking into bringing food and water. Dehydration happens fast when you cycle longer distances, and unless you keep your heartrate low you'll slowly use up your stored short term energy stores.
Specifically to your question: given your age and the fact that you've done a year of cycling already, just go for it. There is no shame in taking a break for a few hours at the halfway point. Make sure you bring food (bananas are your friend) and plenty of water. (750-1000ml an hour if you cycle fast). Just keep your legs moving and you'll get there.