Outsourced IR firms

I am interviewing for a position at an outsourced IR firm (e.g. - ICR, Blueshirt Group, Sapphire, Teneo). Is taking this role going to be a good foot in the door for IR? Could I leverage this experience to get an in-house IR role at an S&P 500 company down the line?

I’m only apprehensive because I know a lot of these roles end up doing low value-add admin work and I worry that many top IR positions at big companies might not view the experience favorably.

For context, I have about 6 years of sell-side ER experience. I’ve been trying to break into IR for the last 18 months and have been struggling.