It depends on the exercise, since some muscle groups are stronger than others. Some may need 12, some 20. Why not get a pair of adjustable dumbbells? It comes out cheaper than to keep buying heavier pairs. Something like this: https://www.amazon.com/CAP-Barbell-RSWB-CS040T-Adjustable-Dumbbell/dp/B0083QZA6W
Some weight-adjustable dumbbells. This way you can change the weight because your legs for example can do much more weight than your biceps. If you can find a cheap bench, that would be great too, because on of the best bicep workouts is on a bench. You incline the bench a little bit, right before 90 degree angle, lock you arms, and curl up, bring dumbbells down slowly, lock your arms, then repeat.
Now you can get something like I have and get these type of adjustable dumbbells https://www.amazon.com/CAP-Barbell-RSWB-CS040T-Adjustable-Dumbbell/dp/B0083QZA6W/ref=sxin_15_ac_m_pm?ac_md=2-0-VW5kZXIgJDIwMA%3D%3D-ac_d_pm&cv_ct_cx=adjustable+dumbbells&dchild=1&keywords=adjustable+dumbbells&pd_rd_i=B0083QZA6W&...
Or, you can get these https://www.amazon.com/Bowflex-SelectTech-Adjustable-Dumbbells-Pair/dp/B001ARYU58/ref=mp_s_a_1_3?dchild=1&keywords=adjustable+dumbbells&qid=1606171267&sprefix=adju&sr=8-3
I personally like the first ones bette because you can buy more plates if you need to.
As for the bench, I have something like this https://www.amazon.com/FLYBIRD-Adjustable-Workout-Multi-Purpose-Foldable/dp/B07HNLBZ4Y/ref=mp_s_a_1_1_sspa?dchild=1&keywords=cheap+workout+bench&qid=1606171493&sprefix=cheap+workout+b&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXV... works amazing.
I’m in lockdown again too. You live in Philadelphia?
there are a lot of options for adjustable weights. Cheep, easy, flexible and will be better then nothing. Walmart even sells them, here is a link for an example - Amazon link
Here is a 3 day split that requires dumbbells and a bench with video guides, might be a good start - Link