It's not so easy and it's not an investment.
The point is, no watch is guaranteed to raise in value, but the ones that may do so, are already very hard to purchase at retail price - means you need to buy a lot of "not investment products" in order to be offered those pieces.
For example, the Rolex Daytona "Panda" (retailing around 17k USD, secondary market price around 30k), the store manager told me it needs 350k USD purchase history to be put in the list to be able to buy it in the future.
Of course, that depends on the retailer, the country, etc.
But this is Rolex: for higher level brands like Patek and AP it's much, much harder to get on-demand pieces (in AP, I was first offered a 490k$ piece in order to "unlock" a Royal Oak worth 40k).
On the other hand, with a retailer where I have purchase history, I got offered a Daytona at 38k which would be worth around 50k to resell. But, if you account the purchase history with other watches and jewelry, my ROI would still be negative.
If, on the other hand, you plan to buy on secondary market and resell on secondary market - so, just hoping to monetize a market trend, keep in mind that you're paying the store fee twice (and they're the ones making the real money).
Chrono24 prices are fine when you buy. But when it's time to sell, account for 70-80% of that price, because the retailer buying it from you needs to have his margin.
And, in this disadvantaged position, you also hope for a market raise to not only recover your losses, but even make a profit. While it's technically possible, I don't believe there's pieces obviously going to raise in price, especially for smaller price points.
Some Pateks were built in very limited supply, sure, they may raise in price.
Rolex makes millions of pieces, so you're actually betting the market demand will increase faster than their production. Good luck with that.
So... If you like watches, go for it, but it's not an investment strategy.