Just to add some more food for thought to consider. I ride a 56cm Tarmac. I'm 180cm with a 87.6 cm inseam measured from the floor to snug in the crotch. (without bike shorts or heavy layers of clothing on.)

Since getting it new in 2020, I've put shorter 165 cranks on it and narrower bars from 42cm to 38cm. When I got it, Specialized showed me as being in the overlap of a 56cm and a 58cm frame. However I've always regretted not trying out a 54cm frame.

As far as you being flexible. I don't think that matters. I can't get my hands halfway down my shins on a good day. And I have long arms too. However I really like the large amount of saddle to bar drop that the low frame stack of the Tarmac allows me. While others use not being flexible as a excuse for sitting more upright, I think it's just more that you have to like the very head first position it puts you in.

My previous bikes were all old style bikes from the 70's. And way oversize for me. The one I rode for 35+ years was a 65cm bike. When I got rid of it, I went to a 59cm and a 60cm bike. They also like the other huge bike frame comfortable... to me. But they road like a luxury sedan on the road. Although the 59 cm Raleigh Competition was a little more sportier of them all. None have been as much fun to ride as my Tarmac.

Still wish I'd tried the 54cm model. However that might have given me too much drop from the saddle to bars.