How do I set up 3 monitors to a Mac Mini I have 3 monitors which I want to connect to my Mac Mini. 2 x HP and 1 x DELL. All 3 monitors have HDMI cables.

I already have a Thunderbolt adapter but it only has one HDMI port.
The adapter is plugged into the back of the mac using the thunderbolt connector.
I currently have one HP monitor connected directly to the mac mini, via HDMI cable and port.
I have the second HP monitor connected to the adapter via HDMI cable, using the adapter HDMI port.

I want to attach the third monitor now. Thought I could just buy a new adapter which would have 3 HDMI ports and connect that directly to the Mini, but can't find this type of adapter on the market. After reading some of the previous queries on here, not sure that will even work.
My third monitor is a DELL and has the following ports:
DP In
DP Out
HDMI (which is what i wanted to use as i already have cable)
3 x USB slots

My current Thunderbolt adapter has a VGA port but no VGA port on the DELL monitor so can't use that. It also has HDMI port, which I'm already using for another monitor, and then it has a DVI port.

So think I need to purchase a new adapter to connect all 3 monitors, but can't find one on the market. Is there a different solution? Any ideas?
Not 100% certain but think you probably need a Thunderbolt PCIx expansion enclosure with 3 or more slots so you can add something like a Blackmagic HDMI display card. There may be less expensive options available but I have been looking into adding more HDMI input ports to my MacPro and this was one of the few options I found.