Hi there, 4.5 months is still really really young, and waking every two hours is totally normal and may well continue for many months more.
Not trying to depress you, but to shift expectations.
The reality of sleep and evenings with babies is one of the biggest things that parents aren't prepared for, because hardly anyone gives realistic information on the normal number of wake ups etc. It's far less stressful to just accept that you'll need to go to bed earlier, and the bedroom will be shared for a good while, and then move onto helping them feel safe sleeping away from you once they're developmentally ready to do that, which is usually well after a year old or even two.
Please ignore anyone telling you to do controlled crying/cry it out, it's absolutely not advised for babies younger than 12 months, and even then there are many good reasons to not do it at all. With a young baby like this they will have no clue what is happening or why and you will just create a massive amount of distress until they exhaust themselves. That's generally what happens unless, someone has an unusually chilled baby.
Next piece of advice- ignore this whole 'rod for your back' thing. It comes from misinformation that expects babies to sleep like adults. We don't do this for things like eating or excreting, yet we're forcing them to do it with sleep. Just like changing nappies is tedious but we wouldn't leave them in their own mess for hours until they learned to hold it in; I cannot understand why people will something very similar with sleep.
There's absolutely nothing wrong with always soothing your child to sleep gently, even for years. Yes it can be very tiring but it always gets better over time (even if incrementally).
For many people co-sleeping goes on well into toddler-hood and that's fine too. There is no rule you have to put them in a separate cot or separate room.
Ask yourself why you want to do the cot thing. Can you make the situation better if there's something specific bothering you? Is it worth the distress it will cause? This stage will go very fast- the days are long but the years are so short.
Good luck