If you think it's too hard to survive near the Ottomans can't you just play on easy mode? That's what the difficulty settings are for.
Have play tested Very Easy just for that purpose, to see what changes, even went a step further with Lucky Nations turned off.
One significant change - Ottomans finally has rebellions spawn in their territory (normal/Ironman game with Lucky Nations "On" - Ottomans rarely ever have rebellions spawn inside their territory due to various buffs to include Lucky and often AI takes Humanism Idea track - which is a party foul for Muslims but the AI doesn't know better than to give itself a numeric advantage).
While a Very Easy player gets 50% boost to total Manpower and Manpower Recovery, that still doesn't match Ottomans' refresh rate for new troops, plus the economic advantages of Ottomans stack-wiping opponents vice only small attrition on their own armies. Important to see how that math game plays out as disadvantageous to a Player, even in Very Easy mode, as - a smaller opponent with lots of allies, can still lose to Ottomans even when having DOUBLE the manpower (starting total army, or even double the army size going into a battle). Point is - stack wipes mean you must fork over cash for new units, even if your manpower pool is on steroids to regenerate (your CASH FLOW is not on 50% regen rate, if you see the point). So you get drained to nothing, must take loans to even eek out 25-30% low success victories even in Very Easy mode, can lose entire allies' kingdoms in the process also. I've seen this first hand - you the player get 1-2 provinces in the final peace deal accepting only a 30% victory, whereas Ottomans may have gained 4-6 new provinces from your small allies, perhaps even a total annexation of them, prior to the final peace deal. That's 2 steps forward, 6 steps back.
As for players who say they can "win" against Ottomans even in Normal/Iron Man, the odds are not with them, but it is possible. Any player of any skill level can beat Ottomans - lottery odds below 1% to maybe 25% chances if you go early, or really understand the game's Personal Union system (not an exploit but not as often exploited for its power-gain pace compared to normal conquering pace). As example, I could start as Byzantium, marry Poland and get a miraculous PU, maybe even control Lithuania also, and then - it's a totally different game. So all the comments about the "possibilities" still don't get to the heart of the matter, and that is - Ottomans were developed to be overpowered at game release, Lucky Nations buffs compensated for some design flaws and PDX wanted some aspects "on rails" so certain nations "always win out" more of the time (not always, but %s are with the Lucky ones), and when you add up all the DLCs and power shifts, Ottomans stands as much if not more overpowered than EU4 at Day 1 game release many years ago. The Dev's basically never solved the problem of an overpowered Ottomans, some gamers who can beat them in select/low-probability ways puff up their chest and some even resort to denigrating posts in this forum and at Steam, if you can't accomplish it, and also - there are complaints about any change to Ottomans from a very vocal bunch of gamers (not just those who live in Turkey).
Everybody wants their "favorite nation" to win - and I don't mean Kingdom, I mean nation. As in - where they live now, there is often a bias to want to play your hometown nation's area in EU4 and conquer the region, conquer the world. For the tiny kingdoms surrounding Ottomans - it just isn't probable, statistically, in this game, so we end up with multiple biases for/against an overpowered Ottomans at the default game start, and since PDX falls into the same trap as RPGs in that any buff tends to remain permanent -- the Dev's never sorted out a way to diminish Ottomans' power as the EU4 timeline moves into periods where Ottomans historically began to wane and lose control.
Short of building an entirely new game in EU5, what the Dev's could do - could turn "Off" Lucky Nation buffs for certain nations at certain dates in the total game's timeline. And could have "always On" events that force a whittling down of power for that kingdom (although a gamer playing that kingdom would not appreciate such an event, so there could be a selector switch On/Off in game setup for this). But these are wishful thinking. Frankly, I think we're stuck with the game-we-have until a totally new EU5 build brings more balance and dynamic buffs up AND down along the entire era's timeline, along with other necessary changes, too long to list in this already overly wordy response.