As I mentioned on the previous post, these exercises are what I teach someone during personal training session who seek for general fitness. So they are basic movements yet so important.
Plank
plank 
alternative birddog
I believe plank is the best exercise for your abs. However, one thing you may have to consider is having high blood pressure.
Anyone who has high blood pressure, then performing isometric training methods is generally out (eg plank). In this case, try birddog. It is relatively safe.
- Duration (for Plank) 30 – 45 seconds
- Set 2 – 3
- Repetition (for Birddog) 6 – 10
- Set 2 – 3
Side plank
side plank 
alternative pallof
These above are anti rotation exercises which target the side of your abs. If the side plank is too challenging, you can perform it with your knee on the floor, too.
However, again this is isometric training like plank. If you have high blood pressure, I would suggest Pallof instead.
- Duration (for side plank) 20 – 30 seconds
- Set 2-3
- Repetition (for pallof) 8 – 12
- Set 2 -3
Side leg raise and Reverse fly
side leg raise 
reverse fly
I added these two exercises for general fitness. Side leg raises to target, gluteus medius / minimus, reverse fly to target trapezius and rhomboid. These muscles are not particularly trained by the other exercises I explained earlier.
- Repetition 12 – 15
- Set 2 – 3
Stay healthy during this lockdown!!!