The Affinity Photo bilateral blur filter comes with two options but they are very powerful features radius & tolerance. The effect is for edge preserving and noise reducing.
Push up the tolerance and radius to the max and you will see horizontal and vertical effect and very little image (but also very little noise). Now if you use it with a little more restraint such as reducing the tolerance down (at zero you will see no effect at all) to about 30% and radius at the max you will see a lot more but any text will still be generally visible as well as any edges. Even with a low radius, you can see the vertical and horizontal effect. By setting the radius high and tolerance low you can create a sort of mist with the flat parts (such as walls) of an image with the edges still fairly clear.
As with any of the tools in this excellent application, you can always use the effect more than once and combine that effect with multiple applications such as using low settings five or six times over.
Another option for the destructive effect is to use it on a duplicate of the original image layer and then apply to that and then you can either remove the effect or you can also use the effect with blending modes for the layer as well as change the opacity and so the effect can be seen in darken or lighten etc. Layer menu and duplicate and then apply it and set radius and tolerance and apply and then go to the layers panel and set the blending mode and opacity (such as contrast negate)
You can also do much the same with the effect but via the live filter layer in the layer menu and you can then apply a non destructive effect as well as use blend modes as well as re-position the effect and how it is applied to the layers as well as the layers below. Select image layer and then layer menu and new live filter layer and then the effect and update the radius etc as well as the blending mode and opacity which is available with the live layers
You can also use type / text, simply add a large font design into the middle of your image and then add the effect and the type will remain only lightly touched for many settings though that can be changed by adding noise and color to the type and then the type can be changed in a more extreme way.
If you use the live effect and combine that with the type then the type will appear far more ghostly with the radius and tolerance set to the maximum or with a glow if the blend mode is set to screen.
The effect can be added multiple times to type / artistic text and can be used to create all kinds of unusual edge effects (as with the image of some text on the right). Create some text and go to the layer menu and merge down and filters menu etc as before and re-apply over and over to create unusual effects