Q.Can I train a well established fig tree?
We recently bought a house with a fantastic fig tree against our back wall. However, it’s a bit large for the space and takes up half of our terrace. I’m looking for advice on how to make it fit better in the space. I understand you can espalier fig trees but also understand that’s usually done when the tree is young. As you can see, this is a well established tree. Can I still espalier this one? Or would it be better to cut it back? Not familiar with fig trees so don’t want to ruin it, just need it to be smaller and/or more against the house. THANK YOU in advance!

As you sense, it is best not to do extreme pruning or try to espalier a mature tree. You can do light "crown reduction pruning by selectively shaping the tallest and widest branches by no more than 25% of each branch and no more than 25% of the foliage removed in a one year period.
If you go more extreme than that, it will distort the natural form and beauty and create a vigorous growth response in the spring. The result will be rampant re-sprouting and you will create a thick and unattractive foliar crown and a lot more maintenance.
If it is really an unacceptable obstruction, an alternative would be to remove the existing tree and start over with a smaller species of tree or shrub or vine.