If the PCIe slots in that board are PCIe 2.0 I can almost guarantee it isn't going to work because there are even a lot of much newer boards, ESPECIALLY OEM models, that even have 3.0 slots but lack BIOS support for 3xxx series cards. Not to mention, there is no way that anything designed for or compatible with that old of a platform could in any way even remotely keep up with with a 3060 so you would in essence be intentionally installing a very bad bottleneck, if you could even get it to work, which is decidedly unlikely.
I mean, that's a 9 year old platform. Most those OEMs don't support BIOS updates for more than two or three years at best. If there is a BIOS update for that board that is newer than the release data of the 3xxx series cards then you MIGHT get it to work, but you'd still have a terrible unbalanced system. You'd be better off with almost anything from a Ryzen 3 or i3 from the last couple of generations than even the best of what could have come in that Optiplex 9 years ago.