That sort of hard pruning is known as renovation, and is usually carried out during winter rather than autumn - if you do it, you are unlikely to see any flowers for up to 3 years.

These shrubs are normally pruned back immediately after flowering, when selective cutting out of some stems to ground level can be done, as well as cutting back flowered stems to a strong bud. More information on that in the link below

https://www.rhs.org.uk/advice/beginners-guide/pruning-plants/pruning-shrubs

I would want to prune it after leaf drop so you can see the bare structure. If you feel you need to drastically prune then I would take out one third and then take some more over the next two years.

I agree with both of the above. I did this to an old one over 3 yrs and it is very happy now and I prune it after flowering.

Oh! I've been naughty & pruned the shrub, I hope it will be ok? I didn't prune it down to much.
As you can see, I've added some pictures of Before & After for you to see :o)).
And while I was pruning away I noticed Foxy has made a whole in the fence so now that has to be replaced & the trellis on top Grrrr!

Looking at the pictures I would, renovate this wiegelia further down to a foot from ground, take out any dead stuff out at the base, this will soon respond in the spring and probably will not flower next year but I have known wiegelieas flower after renovation pruning, either way once it does flower then trim and keep it to the desired height you want, it’s only a small area so don’t let it get too big, is this weigelia Bristol ruby? Wiegelias are very simple to propagate either hard wood or semi ripe cuttings, you can also be ruthless with the euonymus by the side of it so this small area looks balanced, it has some reversion so cut this out from where it starts otherwise it will take over and the variegation will be lost.

Julien. Thanks for the info, I will cut the shrub down lower, I don't mind if it doesn't flower :o)). I have cut the euonymus down quite a lot, I took out all the green but may cut it down even further :o)) I have a what looked like dead Tree Peony but have noticed new growth, I have cut out all the dead stems that I can see. :o))