Austin Regional Clinic (ARC) policy with HMOs and referrals

I’ve been going to my PCP at ARC for years. It’s ACA insurance time and I’m down to my final few choices. One of them is an HMO. My question for anybody who goes to ARC and uses an HMO: Do you know if ARC docs tend to only make referrals to specialists who work for ARC? Are they willing to take suggestions for specialists outside ARC, if you have one you’ve used in the past?

Thanks in advance