This. Simple hormone panel should suffice for most issues. Can always get more tests done if needed. But it could be as simple as just a test:dht:estro issue. Though it couldn't hurt to get cbc and Chem panel done just for overall health purposes.Since this is for a specific issue you wouldn’t really need to get all that blood work at once.
I’d go with serum and free testosterone as well as a sensitive e2 panel. After that I’d look at prolactin/DHT/SHBG based on the results of the testosterone/e2.
There’s so much that can go into sex drive and function though (dopamine, serotonin, norepinephrine, NO, and ACh to name a few and potentially a lot more) along with all the typical hormones so I agree that blood are probably the best starting point but they may very well not reveal anything.
At that point you gotta go back to throwing things at the wall and see what sticks which is what I’ve been doing. Gotta love the human body lol