Hey! Welcome to the world of #fountainpens.
I have never myself used a Platinum Plaisir so I might not be of particular assistance with that pen, however "hard starting" is a somewhat common problem that can often be fixed. One of the most common recommendations to pull apart the pen and carefully clean the feed, often hard starting is a result of poor ink flow through the feed. It could be that the nib is not well adjusted, there are a plethora of nimb adjusting videos to be found. Doodlebud, is one of my favorite sources of knowledge, can be found on YouTube. If you want to be able to use bottled ink you need a converter, specifically the Platinum converter which works, I believe, in all Platinum fountain pens.
Once you can experiment with bottled inks, you might find that a wetter ink will work well in your pen. My first pen was a pilot metropolitan, it has the opposite problem; far too much ink flow. I use a very dry ink called Celadon Cat by Diamine, it has fixed the problem.