I used to play it a lot in Legion and use it as alt in BfA.
The AoE killing potential is rather slow. What you do is consecration and attack things one by one, potentially getting holy prism talent and using it on yourself (So it hits 5 enemies near you). While doing this, if you have glimmer, get it on several units and keep it going. Twilight devastation really helps.
In single target however, paladin is pretty good. Very good in fact. You can do 80% of performance of a dps spec to a single target, specially with cooldowns.
Given this, yes you can do solo content with ease. Rexxar is very easy to holy paladins, as entering visions as solo healer reduces the damage and healing of all enemies in vision by 40% and as holy you can burst him down like no other class. If you divine shield when he summons the first boar, you can kill him before divine shield duration ends. The same goes for rest of vision of N’zoth. Don’t pull too much, and focus on bosses. Its easy.
WQ are easy as well. Its slightly slow, but you can never die and single target is as good as a dps.