If it's purely DNS blocking (no IP redirection or blocking), your own recursive resolver (eg, unbound) shouldn't be affected, assuming the ISP doesn't also intercept unencrypted DNS queries. If there's also interception, encrypted DNS upstream might help (assuming they're not blocked entirely, repressive countries do this, so far not in EU)

I don't think any of them will help in Spain case though, I believe the ISP/court choose to block the IP range entirely, which hit Cloudflare customers. DNS hijinks won't solve those.