I'm currently using an Airport Extreme 5th gen and I wanted to extend the wi-fi range.

So I purchased an Airport Express and hooked it up in bridge mode which worked, but when I do a speed test i'm only getting 94mbps, but when I disconnect the Airport Express and do another speed test through the Airport Extreme I get 250mbps. I was reading online that the Express can only handle up to 100mbps through the Cat5E so I'm guessing this is all I'd achieve.

This is correct. The Express has only 100 Mbps Ethernet ports so in theory, that would be the maximum speed that it could achieve.

My question is if I were to purchase another Airport Extreme and use that to extend the Wi-Fi range can I expect faster speeds or would it be the same as the Express.

If you could locate a refurbished or used 5th Gen AirPort Extreme in good condition, you could expect the same performance that you are currently receiving from your existing 5th Gen AirPort Extreme.

A new AirPort Extreme would provide essentially the same performance.