I would caution anyone older increasing their rbc numbers. You run the risk of blood clots and all their horrible effects on health that we are all aware of.
That said, simply injecting a trt dose of 100mg testosterone will most definitely raise rbc levels so high you will need to donate at the red cross routinely.
Its your health and if want to risk the health risks which are very real, then its your body. Unless you have clinically low numbers and health effects of low rbc values, I would leave it alone. If you have a clinical issue then a doctor is in order.... But there seems to be a common thread on this forum of a mentality of avoiding doctors and treating ailments by eliminating sugar or taking megadoses of zinc and things like that.
I disagree. If you're older and RBCs have exhibited an age-related decline, and if you're using dietary means to increase them, which is lowest risk, it should improve health, not make it worse. I'd definitely caution against using drugs to increase them though, that's not what I'm suggesting.