I do most of my Audio work in Adobe Audition, but the free Audacity is a good choice too. Those accept VST's, and there are tons (many free) available on the Internet.
Now, within PrE, the Audio Effect>Reverb can be very useful, as can Audio Effect>Delay.
In Reverb, Pre Delay and Size are probably the two settings to experiment with most.
With Delay, the Delay time is probably the parameter to experiment with.
If you are not quite getting what you want, a technique that I use with DD 5.1 SS, is to Duplicate the Audio Clip, placing that onto another Audio Track, apply Reverb and Delay to it, attenuate, adjust the Volume of the Duplicate Clip down, and if necessary, for the "echo," then turn Snap OFF, and nudge that Duplicate Clip just a bit to displace it a bit.
Audition, Audacity, or many other audio-editing programs offer many more capabilities, and especially with add-on VST's.
No reason to make it harder than it is. The Reverb audio effect is exactly what you need. It can be customized so that it sounds like a smaller room, a larger room or a large hall or church.
Just drag the effect onto the audio clip on your timeline.
That was my first option, but I find it to be lacking, hence my mention of audio-editing programs, that can easily take it beyond.
For the OP, Reverb with some tweaking, might be all that is required?
Thanks that works. What is DD 5.1 SS?
Sorry about the jargon. "DD 5.1 SS" = Dolby Digital 5.1 Surround Sound.
Glad that you could create the "echo," that you needed.
Happy editing and good luck,