It is possible to apply under the EU settlement scheme from outside the UK.

You need to be able to use the EU Exit app, that means having a suitable NFC enabled Android phone or iPhone or being able to borrow one

EEA and Swiss nationals must have a valid passport or ID card with a biometric chip that can be read by the app;

Non EEA nationals must have a valid biometric residence card with a chip.

If you are unable to apply using the above, you need to contact the resolution centre.

Close family members who are, themselves, EEA nationals must apply for pre-settled status from abroad, before travelling to the UK.

See: EU Settlement Scheme: applying from outside the UK - GOV.UK

Using the app to apply