I'm afraid you're going to have to live with the simplified 0700 permissions via SMB on the macOS side if you want to keep things simple.
If you want to be able to manage the permissions more granularly from macOS over SMB, you'll need to enable Advanced Permissions (not the Windows ACLs, they're something else) on the QNAP NAS which are POSIX ACLs and then you're in for quite a bit of pain. For one thing, macOS uses NFS ACLs which are richer than POSIX ACLs and don't map 1-to-1 between them. Second, if there are other non-macOS clients to the SMB server, they may not handle the ACLs well or at all and you may run into permissions issues. Third, I think it's recommended to make the NAS an Active Directory Server and have the macOS clients be members of this ADS so both the macOS clients and the NAS all use the same users and groups for ACLs, otherwise they're disparate and it can quickly become a big mess.
Don't take my word for it. I can't tell you much more than that as I don't have much experience with this setup on QNAP NAS. I'm aware that it's a can of worms.
For this reason I don't use QNAP's Samba server, instead I run my own Samba server that I can configure at will. I'm using this configuration, which preserves POSIX permissions between Linux and macOS in both directions, without any complicated ACL or ADS setup:
while QNAP uses
There may be other QNAP settings that would need to be changed, I don't know.
So with my configuration, a normal file has the correct 0644 permissions, an executable file has the correct 0755 permissions and so forth. I can chmod from the macOS side and the permissions are reflected on the Linux side.
You could try to apply the same configuration on your NAS, but do it at your own risks, I have no idea what the results will be - good or bad.
I don't use QNAP's SMB server, can't help you with deviating from its standard configuration too much.