Timmsoski recently did a video tutorial for how to set up your pro as a real rider. Part of that is to make the whole calendar available, which is what applies to you. That part starts at ~7 minutes.
If I understand it correctly, what you need to do is go to Team Races, filter for your team, and then in the column to the far right (fkIDpro_cyclist), put a 1 in the NC for your country (forces you to ride it), a 7 in all other NCs (makes them unavailable to you) and a 6 for every other race (makes them available to chose) except for the REJECTED races, where you leave a 0. You can then go to GAM_career_data and increase the value in PROPOINTS to have enough points to chose all the races you want.
This unlocks the race calendar without changing your cyclist's level. If you want to do that as well, go to CYN_procyclist and change value_i_xp to something bigger. Don't know if you get to spend the XP or if you just go to that higher level with your base stats.
Hope this is comprehensive, if not, just watch the video. Or do that anyway, Timmsoski makes good content
I have a related question but not exactly the same: how do I manage in Fast Editor to let me run all races with Level 1 in Pro Cyclist mode?
I'd like to make my young rider run in a WT but from Level 1 (I did this part), but now I'd like to edit the races as I'd like to run Giro or Tour with low skills at the beginning, like in real life for the most of cyclists.